Merge pull request #141 from realnc/fix-stdc-format-macros

Fix warnings about redefining __STDC_FORMAT_MACROS

Author: inactive123

include/retro_common_api.h

@@ -89,7 +89,9 @@ typedef int ssize_t;
 /* C++11 says this one isn't needed, but apparently (some versions of) mingw require it anyways */
 /* https://stackoverflow.com/questions/8132399/how-to-printf-uint64-t-fails-with-spurious-trailing-in-format */
 /* https://github.com/libretro/RetroArch/issues/6009 */
-#define __STDC_FORMAT_MACROS
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS 1
+#endif
 #include <inttypes.h>
 #endif
 #ifndef PRId64