tools: clean up mingw ifdefs

We have a header file specifically for mingw cruft, so keep it there
to avoid crap spreading into the main tools.  This lets our devs just
worry about *nix systems.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/tools/mingw_support.h b/tools/mingw_support.h
index ee07290..48b8010 100644
--- a/tools/mingw_support.h
+++ b/tools/mingw_support.h
@@ -34,6 +34,14 @@
 #define MAP_SHARED	0x01		/* Share changes */
 #define MAP_PRIVATE	0x02		/* Changes are private */
 
+/* File perms */
+#ifndef S_IRGRP
+# define S_IRGRP 0
+#endif
+#ifndef S_IWGRP
+# define S_IWGRP 0
+#endif
+
 /* Windows 64-bit access macros */
 #define LODWORD(x) ((DWORD)((DWORDLONG)(x)))
 #define HIDWORD(x) ((DWORD)(((DWORDLONG)(x) >> 32) & 0xffffffff))