GN Mac build work

tools/gn/secondary/build/config/compiler/BUILD.gn

Index: tools/gn/secondary/build/config/compiler/BUILD.gn
diff --git a/tools/gn/secondary/build/config/compiler/BUILD.gn b/tools/gn/secondary/build/config/compiler/BUILD.gn
index 6174b2e7333dc03c62c6c6e8aad3dfac8ab40341..ef9d61f9f01382faf5a06fee8ead1766705aa43a 100644
--- a/tools/gn/secondary/build/config/compiler/BUILD.gn
+++ b/tools/gn/secondary/build/config/compiler/BUILD.gn
@@ -116,9 +116,7 @@ config("compiler") {
 
     # Clang-specific compiler flags setup.
     # ------------------------------------
-    # TODO(brettw) these should be clang-only. For now, make it mac-only since
-    # that's where we always use clang.
-    if (is_mac) { # if (is_clang) {
+    if (is_clang) {
       cflags += [
         "-fcolor-diagnostics",
       ]
@@ -301,7 +299,7 @@ config("default_warnings") {
 
     # TODO(brettw) Ones below here should be clang-only when we have a flag
     # for it.
-    if (is_mac) { #if (is_clang) {
+    if (is_clang) {
       cflags += [
         "-Wheader-hygiene",