Support clang-cl build on Windows.

testing/gtest.gyp

Index: testing/gtest.gyp
diff --git a/testing/gtest.gyp b/testing/gtest.gyp
index 3c01552c4c49a5478596bbb2266e45f1ce28f733..c1f58ba293e42f94f9f02ebff9bcd61f2fd3adba 100644
--- a/testing/gtest.gyp
+++ b/testing/gtest.gyp
@@ -142,6 +142,12 @@
         ],
         'msvs_disabled_warnings': [4800],
       },
+      'variables': {
+        'clang_warning_flags': [
+          '-Wno-reorder',
+          '-Wno-unused'

[Nico, 2016/03/09 02:30:19]

We only need the first of these two in chromium's src/testing/gtest.gyp, and the
first one has a nice comment there

[Oliver Chang, 2016/03/09 17:00:17]

Added comments.

We need both here for some reason. Perhaps the version of gtest here is
different?

+        ],
+      },
     },
     {
       'target_name': 'gtest_main',