Provide OS_ and COMPILER_ macros for OS and compiler differentiation
Review URL: http://chrome-reviews.prom.corp.google.com/1108

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@338 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/port.h b/base/port.h
index db688dc..12b2a90 100644
--- a/base/port.h
+++ b/base/port.h
@@ -30,7 +30,9 @@
 #ifndef BASE_PORT_H__
 #define BASE_PORT_H__
 
-#ifdef MSC_VER
+#include "build/build_config.h"
+
+#ifdef COMPILER_MSVC
 #define GG_LONGLONG(x) x##I64
 #define GG_ULONGLONG(x) x##UI64
 #else