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

build/config/win/BUILD.gn

Index: build/config/win/BUILD.gn
diff --git a/build/config/win/BUILD.gn b/build/config/win/BUILD.gn
index 940e55c6c28f033dea5235f08f78ca4df6b6c6a5..6d48b51032856d549f457f37fc44116ca8b59e58 100644
--- a/build/config/win/BUILD.gn
+++ b/build/config/win/BUILD.gn
@@ -436,3 +436,21 @@ config("midl_warnings") {
     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") {
+}