Add closure for WCHAR_MIN/WCHAR_MAX in wchar.h


git-svn-id: svn+ssh://svn.code.sf.net/p/mingw-w64/code/trunk@609 4407c894-4637-0410-b4f5-ada5f102cad1
diff --git a/mingw-w64-headers/include/wchar.h b/mingw-w64-headers/include/wchar.h
index 564587d..e67cd4a 100644
--- a/mingw-w64-headers/include/wchar.h
+++ b/mingw-w64-headers/include/wchar.h
@@ -14,8 +14,10 @@
 extern "C" {
 #endif
 
+#ifndef WCHAR_MIN  /* also in stdint.h */
 #define WCHAR_MIN 0
 #define WCHAR_MAX ((wchar_t) -1) /* UINT16_MAX */
+#endif
 
 #ifndef __GNUC_VA_LIST
 #define __GNUC_VA_LIST