fix mixing up of SDL and libc allocators, proper flushing of quad build buffers

src/twn_util_c.h

@@ -11,6 +11,10 @@
 #define MAX SDL_max
 #define MIN SDL_min
 
+void *cmalloc(size_t size);
+void *crealloc(void *ptr, size_t size);
+void *ccalloc(size_t num, size_t size);
+
 void cry_impl(const char *file, const int line, const char *title, const char *text);
 #define CRY(title, text) cry_impl(__FILE__, __LINE__, title, text)
 #define CRY_SDL(title) cry_impl(__FILE__, __LINE__, title, SDL_GetError())