clang/win: Build chromium code without -Wno-incompatible-pointer-types.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 09a26a451401057297cbba31da03bcf0015d7a34..cc55e650953fd28762d23fe117b1609dce368881 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -802,7 +802,6 @@ if (is_win) {
       "-Wno-empty-body",  # http://crbug.com/504661
       "-Wno-extra-tokens",  # http://crbug.com/504663
       "-Wno-ignored-attributes",  # http://crbug.com/504695
-      "-Wno-incompatible-pointer-types",  # http://crbug.com/504696
       "-Wno-int-to-void-pointer-cast",  # http://crbug.com/504697
       "-Wno-invalid-noreturn",  # http://crbug.com/504698
       "-Wno-logical-op-parentheses",  # http://crbug.com/504699
@@ -978,6 +977,10 @@ config("no_chromium_code") {
   cflags_cc = []
   defines = []
 
+  if (is_clang) {
+    cflags += [ "-Wno-incompatible-pointer-types" ]
+  }
+
   if (is_win) {
     cflags += [
       "/W3",  # Warning level 3.