(Do not land) Very hacky patch for using -fprofile-functions in the Win-Clang build

build/config/win/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/win/visual_studio_version.gni")
 import("//build/toolchain/toolchain.gni")
 
@@ skipping 418 matching lines @@
 
 # Internal stuff --------------------------------------------------------------
 
 # Config used by the MIDL template to disable warnings.
 config("midl_warnings") {
   if (is_clang) {
     # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
     cflags = [ "-Wno-extra-tokens" ]
   }
 }
+
+# Instrumentation -------------------------------------------------------------
+
+config("default_cygprofile_instrumentation") {
+  if (use_order_profiling) {
+    configs = [ ":cygprofile_instrumentation" ]
+  } else {
+    configs = [ ":no_cygprofile_instrumentation" ]
+  }
+}
+
+config("cygprofile_instrumentation") {
+  defines = [ "CYGPROFILE_INSTRUMENTATION=1" ]
+  cflags = [ "-Xclang", "-finstrument-functions" ]
+}
+
+config("no_cygprofile_instrumentation") {
+}