autotools: stop using AC_FUNC_MEMCMP and AC_FUNC_STRTOD

Closes:  https://github.com/libsdl-org/SDL/issues/6266 .
(cherry picked from commit db225dec413c1b637edd61b915f5f066a3dd38d0)

configure

@@ -657,6 +657,7 @@ ac_includes_default="\
 
 ac_header_c_list=
 ac_subst_vars='LTLIBOBJS
+LIBOBJS
 WAYLAND_SCANNER_CODE_MODE
 WAYLAND_SCANNER
 EXTRA_LDFLAGS
@@ -718,8 +719,6 @@ JACK_LIBS
 JACK_CFLAGS
 ALSA_LIBS
 ALSA_CFLAGS
-POW_LIB
-LIBOBJS
 ALLOCA
 CPP
 LIBTOOLLINKERTAG
@@ -19064,198 +19063,6 @@ printf "%s\n" "#define STACK_DIRECTION $ac_cv_c_stack_direction" >>confdefs.h
 fi
 
 
-    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for working memcmp" >&5
-printf %s "checking for working memcmp... " >&6; }
-if test ${ac_cv_func_memcmp_working+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test "$cross_compiling" = yes
-then :
-  ac_cv_func_memcmp_working=no
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$ac_includes_default
-int
-main (void)
-{
-
-  /* Some versions of memcmp are not 8-bit clean.  */
-  char c0 = '\100', c1 = '\200', c2 = '\201';
-  if (memcmp(&c0, &c2, 1) >= 0 || memcmp(&c1, &c2, 1) >= 0)
-    return 1;
-
-  /* The Next x86 OpenStep bug shows up only when comparing 16 bytes
-     or more and with at least one buffer not starting on a 4-byte boundary.
-     William Lewis provided this test program.   */
-  {
-    char foo[21];
-    char bar[21];
-    int i;
-    for (i = 0; i < 4; i++)
-      {
-	char *a = foo + i;
-	char *b = bar + i;
-	strcpy (a, "--------01111111");
-	strcpy (b, "--------10000000");
-	if (memcmp (a, b, 16) >= 0)
-	  return 1;
-      }
-    return 0;
-  }
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_run "$LINENO"
-then :
-  ac_cv_func_memcmp_working=yes
-else $as_nop
-  ac_cv_func_memcmp_working=no
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_func_memcmp_working" >&5
-printf "%s\n" "$ac_cv_func_memcmp_working" >&6; }
-test $ac_cv_func_memcmp_working = no && case " $LIBOBJS " in
-  *" memcmp.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS memcmp.$ac_objext"
- ;;
-esac
-
-
-    if test x$ac_cv_func_memcmp_working = xyes; then
-
-printf "%s\n" "#define HAVE_MEMCMP 1" >>confdefs.h
-
-    fi
-    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for working strtod" >&5
-printf %s "checking for working strtod... " >&6; }
-if test ${ac_cv_func_strtod+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  if test "$cross_compiling" = yes
-then :
-  ac_cv_func_strtod=no
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-$ac_includes_default
-#ifndef strtod
-double strtod ();
-#endif
-int
-main (void)
-{
-  {
-    /* Some versions of Linux strtod mis-parse strings with leading '+'.  */
-    char *string = " +69";
-    char *term;
-    double value;
-    value = strtod (string, &term);
-    if (value != 69 || term != (string + 4))
-      return 1;
-  }
-
-  {
-    /* Under Solaris 2.4, strtod returns the wrong value for the
-       terminating character under some conditions.  */
-    char *string = "NaN";
-    char *term;
-    strtod (string, &term);
-    if (term != string && *(term - 1) == 0)
-      return 1;
-  }
-  return 0;
-}
-
-_ACEOF
-if ac_fn_c_try_run "$LINENO"
-then :
-  ac_cv_func_strtod=yes
-else $as_nop
-  ac_cv_func_strtod=no
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_func_strtod" >&5
-printf "%s\n" "$ac_cv_func_strtod" >&6; }
-if test $ac_cv_func_strtod = no; then
-  case " $LIBOBJS " in
-  *" strtod.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS strtod.$ac_objext"
- ;;
-esac
-
-ac_fn_c_check_func "$LINENO" "pow" "ac_cv_func_pow"
-if test "x$ac_cv_func_pow" = xyes
-then :
-
-fi
-
-if test $ac_cv_func_pow = no; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for pow in -lm" >&5
-printf %s "checking for pow in -lm... " >&6; }
-if test ${ac_cv_lib_m_pow+y}
-then :
-  printf %s "(cached) " >&6
-else $as_nop
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-lm  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-char pow ();
-int
-main (void)
-{
-return pow ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_lib_m_pow=yes
-else $as_nop
-  ac_cv_lib_m_pow=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_m_pow" >&5
-printf "%s\n" "$ac_cv_lib_m_pow" >&6; }
-if test "x$ac_cv_lib_m_pow" = xyes
-then :
-  POW_LIB=-lm
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: cannot find library containing definition of pow" >&5
-printf "%s\n" "$as_me: WARNING: cannot find library containing definition of pow" >&2;}
-fi
-
-fi
-
-fi
-
-    if test x$ac_cv_func_strtod = xyes; then
-
-printf "%s\n" "#define HAVE_STRTOD 1" >>confdefs.h
-
-    fi
     ac_fn_c_check_func "$LINENO" "mprotect" "ac_cv_func_mprotect"
 if test "x$ac_cv_func_mprotect" = xyes
 then :
@@ -19361,6 +19168,12 @@ if test "x$ac_cv_func_memset" = xyes
 then :
   printf "%s\n" "#define HAVE_MEMSET 1" >>confdefs.h
 
+fi
+ac_fn_c_check_func "$LINENO" "memcmp" "ac_cv_func_memcmp"
+if test "x$ac_cv_func_memcmp" = xyes
+then :
+  printf "%s\n" "#define HAVE_MEMCMP 1" >>confdefs.h
+
 fi
 ac_fn_c_check_func "$LINENO" "memcpy" "ac_cv_func_memcpy"
 if test "x$ac_cv_func_memcpy" = xyes
@@ -19541,6 +19354,12 @@ if test "x$ac_cv_func__ultoa" = xyes
 then :
   printf "%s\n" "#define HAVE__ULTOA 1" >>confdefs.h
 
+fi
+ac_fn_c_check_func "$LINENO" "strtod" "ac_cv_func_strtod"
+if test "x$ac_cv_func_strtod" = xyes
+then :
+  printf "%s\n" "#define HAVE_STRTOD 1" >>confdefs.h
+
 fi
 ac_fn_c_check_func "$LINENO" "strtol" "ac_cv_func_strtol"
 if test "x$ac_cv_func_strtol" = xyes

configure.ac

@@ -331,14 +331,6 @@ dnl Check for defines
     AC_FUNC_ALLOCA
 
 dnl Checks for library functions.
-    AC_FUNC_MEMCMP
-    if test x$ac_cv_func_memcmp_working = xyes; then
-        AC_DEFINE(HAVE_MEMCMP, 1, [ ])
-    fi
-    AC_FUNC_STRTOD
-    if test x$ac_cv_func_strtod = xyes; then
-        AC_DEFINE(HAVE_STRTOD, 1, [ ])
-    fi
     AC_CHECK_FUNC(mprotect,
         AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
           #include <sys/types.h>
@@ -347,7 +339,7 @@ dnl Checks for library functions.
         AC_DEFINE(HAVE_MPROTECT, 1, [ ])
         ],[]),
     )
-    AC_CHECK_FUNCS(malloc calloc realloc free getenv setenv putenv unsetenv bsearch qsort abs bcopy memset memcpy memmove wcslen wcslcpy wcslcat _wcsdup wcsdup wcsstr wcscmp wcsncmp wcscasecmp _wcsicmp wcsncasecmp _wcsnicmp strlen strlcpy strlcat _strrev _strupr _strlwr index rindex strchr strrchr strstr strtok_r itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp vsscanf vsnprintf fopen64 fseeko fseeko64 sigaction setjmp nanosleep sysconf sysctlbyname getauxval elf_aux_info poll _Exit)
+    AC_CHECK_FUNCS(malloc calloc realloc free getenv setenv putenv unsetenv bsearch qsort abs bcopy memset memcmp memcpy memmove wcslen wcslcpy wcslcat _wcsdup wcsdup wcsstr wcscmp wcsncmp wcscasecmp _wcsicmp wcsncasecmp _wcsnicmp strlen strlcpy strlcat _strrev _strupr _strlwr index rindex strchr strrchr strstr strtok_r itoa _ltoa _uitoa _ultoa strtod strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp vsscanf vsnprintf fopen64 fseeko fseeko64 sigaction setjmp nanosleep sysconf sysctlbyname getauxval elf_aux_info poll _Exit)
 
     AC_CHECK_LIB(m, pow, [LIBS="$LIBS -lm"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"])
     AC_CHECK_FUNCS(acos acosf asin asinf atan atanf atan2 atan2f ceil ceilf copysign copysignf cos cosf exp expf fabs fabsf floor floorf trunc truncf fmod fmodf log logf log10 log10f lround lroundf pow powf round roundf scalbn scalbnf sin sinf sqrt sqrtf tan tanf)