Fix build on mingw

Bug 561787
diff --git a/qcmstypes.h b/qcmstypes.h
index 26c138a..2d98c0c 100644
--- a/qcmstypes.h
+++ b/qcmstypes.h
@@ -25,9 +25,7 @@
 #ifdef __OS2__
 /* OS/2's stdlib typdefs uintptr_t. So we'll just include that so we don't collide */
 #include <stdlib.h>
-#elif defined(__FreeBSD__)
-/* FreeBSD typedefs uintptr_t in /usr/include/sys/types.h */
-#else
+#elif !defined(__intptr_t_defined) && !defined(_UINTPTR_T_DEFINED)
 typedef PRUptrdiff uintptr_t;
 #endif
 #endif