Revert of Build: Don't pass /GL to Clang on Windows

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 3930c79765d18a00abdad07a9808c5137ccc47a1..fbf6db6ee9313012fee6ac8594e960f05075bf41 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1207,11 +1207,10 @@
   if (is_win) {
     cflags -= [ "/Os" ]
     cflags += [ "/Ot" ]  # Favor speed over size.
-    if (is_official_build && !is_clang) {
+    if (is_official_build) {
       # TODO(GYP): TODO(dpranke): Should these only be on in an official
       # build, or on all the time? For now we'll require official build so
       # that the compile is clean.
-      # TODO(hans): Remove Clang special-case when it rolls past r239656.
       cflags += [
         "/GL",  # Whole program optimization.