Fixed bug 3688 - cmake / pthread check related patch proposal

Juha Niemim?ki

Fix for PTHREAD_MUTEX_RECURSIVE_NP check and restoring the original flags

Two fixes proposed:

1) Looks like there is a copy-paste issue regarding PTHREAD_MUTEX_RECURSIVE_NP check.

2) Compiler flag restoration doesn't look symmetrical regarding if/endif blocks. Moved to an outer block (if PTHREADS).

cmake/sdlchecks.cmake

@@ -931,7 +931,7 @@ macro(CheckPTHREAD)
             #include <pthread.h>
             int main(int argc, char **argv) {
               pthread_mutexattr_t attr;
-              pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+              pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
               return 0;
             }" HAVE_RECURSIVE_MUTEXES_NP)
         if(HAVE_RECURSIVE_MUTEXES_NP)
@@ -960,7 +960,6 @@ macro(CheckPTHREAD)
           int main(int argc, char** argv) { return 0; }" HAVE_PTHREAD_NP_H)
       check_function_exists(pthread_setname_np HAVE_PTHREAD_SETNAME_NP)
       check_function_exists(pthread_set_name_np HAVE_PTHREAD_SET_NAME_NP)
-      set(CMAKE_REQUIRED_FLAGS "${ORIG_CMAKE_REQUIRED_FLAGS}")
 
       set(SOURCE_FILES ${SOURCE_FILES}
           ${SDL2_SOURCE_DIR}/src/thread/pthread/SDL_systhread.c
@@ -977,6 +976,7 @@ macro(CheckPTHREAD)
       endif()
       set(HAVE_SDL_THREADS TRUE)
     endif()
+    set(CMAKE_REQUIRED_FLAGS "${ORIG_CMAKE_REQUIRED_FLAGS}")
   endif()
 endmacro()