Removed fdatasync and gethostname definitions from platforms that don't have them

As verified by CMake builds in CI

include/build_config/SDL_build_config_android.h

@@ -57,10 +57,8 @@
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
-#define HAVE_FDATASYNC 1
 #define HAVE_FREE   1
 #define HAVE_GETENV 1
-#define HAVE_GETHOSTNAME 1
 #define HAVE_PUTENV 1
 #define HAVE_SETENV 1
 #define HAVE_UNSETENV   1

include/build_config/SDL_build_config_emscripten.h

@@ -60,10 +60,8 @@
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
-#define HAVE_FDATASYNC 1
 #define HAVE_FREE 1
 #define HAVE_GETENV 1
-#define HAVE_GETHOSTNAME 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1
 #define HAVE_UNSETENV 1

include/build_config/SDL_build_config_ios.h

@@ -49,10 +49,8 @@
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
-#define HAVE_FDATASYNC 1
 #define HAVE_FREE   1
 #define HAVE_GETENV 1
-#define HAVE_GETHOSTNAME 1
 #define HAVE_PUTENV 1
 #define HAVE_SETENV 1
 #define HAVE_UNSETENV   1

include/build_config/SDL_build_config_macos.h

@@ -54,10 +54,8 @@
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC    1
-#define HAVE_FDATASYNC 1
 #define HAVE_FREE   1
 #define HAVE_GETENV 1
-#define HAVE_GETHOSTNAME 1
 #define HAVE_SETENV 1
 #define HAVE_PUTENV 1
 #define HAVE_UNSETENV   1

include/build_config/SDL_build_config_windows.h

@@ -135,7 +135,6 @@ typedef unsigned int uintptr_t;
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
 #define HAVE_REALLOC 1
-#define HAVE_FDATASYNC 1
 #define HAVE_FREE 1
 #define HAVE_ABS 1
 #define HAVE_MEMSET 1

include/build_config/SDL_build_config_wingdk.h

@@ -75,7 +75,6 @@
 #define HAVE_LIBC   1
 #define HAVE_MALLOC 1
 #define HAVE_CALLOC 1
-#define HAVE_FDATASYNC 1
 #define HAVE_REALLOC 1
 #define HAVE_FREE 1
 #define HAVE_ABS 1