Temporary fix for bug 2494 - Crashes due to the non thread-safe SDL_malloc/SDL_free on Windows

We'll define USE_LOCKS as a temporary fix until an alternative like ptmalloc, jemalloc, or nedmalloc can be investigated.
http://www.malloc.de/en/
http://www.canonware.com/jemalloc/
http://www.nedprod.com/programs/portable/nedmalloc/

SDL allocates memory very infrequently, so this is probably a decent fix for a while.

src/stdlib/SDL_malloc.c

@@ -54,6 +54,7 @@ void SDL_free(void *ptr)
 #define LACKS_STRING_H
 #define LACKS_STDLIB_H
 #define ABORT
+#define USE_LOCKS 1
 
 /*
   This is a version (aka dlmalloc) of malloc/free/realloc written by