Merge pull request #27 from cloudwu/fixbuild

fix build for mingw/gcc (macro xx conflict)

3rdparty/astc/astc_codec_internals.h

@@ -19,6 +19,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <math.h>
 #include "mathlib.h"
 
 #ifndef MIN