Clang static analysis builds should use C runtime directly.

This is a little macro magic to use malloc() directly instead of SDL_malloc(),
 etc, so static analysis tests that know about the C runtime can function
 properly, and understand that we are dealing with heap allocations, etc.

This changed our static analysis report from 5 outstanding bugs to 30.

5x as many bugs were hidden by SDL_malloc() not being recognized as malloc()
 by the static analyzer!

src/stdlib/SDL_string.c

@@ -18,6 +18,11 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
+
+#if defined(__clang_analyzer__) && !defined(SDL_DISABLE_ANALYZE_MACROS)
+#define SDL_DISABLE_ANALYZE_MACROS 1
+#endif
+
 #include "../SDL_internal.h"
 
 /* This file contains portable string manipulation functions for SDL */