Fixed missing alloc macro on mingw32, I think.

CHANGELOG

@@ -4,6 +4,7 @@
 
 -- stuff in the stable-1.0 branch, backported from 2.0.0 dev branch, etc ---
 
+07122007 - Maybe fixed compile on mingw32.
 07112007 - Fixed crash on zero-byte read/write (thanks, Ensiform!).
 05052007 - Fixed zip archiver: could do bogus seek if a small, non-zip file
            got put through isArchive().

physfs_internal.h

@@ -22,6 +22,10 @@
 #define assert(x)
 #endif
 
+#ifdef __MINGW32__
+#include <alloca.h>
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif