Fix webrtc gn windows build.

R=kjellander@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/32779004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7882 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index 5ded359..acce9f0 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -444,8 +444,10 @@
   # compiler settings.
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
-  cflags += [ "-Wno-uninitialized" ]
-  cflags_cc += [ "-Wno-non-virtual-dtor" ]
+  if (!is_win) {
+    cflags += [ "-Wno-uninitialized" ]
+    cflags_cc += [ "-Wno-non-virtual-dtor" ]
+  }
 
   if (use_openssl) {
     public_configs += [ ":openssl_config" ]