Disable new -Wenum-compare-switch on the tot bots.

Bug: 753944,753973
Change-Id: I813ce64b4db8bdef88e633a1b363eafccc8bd026
Reviewed-on: https://chromium-review.googlesource.com/608851
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Hans Wennborg <hans@chromium.org>
Reviewed-by: Reid Kleckner <rnk@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#493150}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 203d085a0f6989b0cb4a2a6e461f5439bfa0285f

config/compiler/BUILD.gn

@@ -1205,6 +1205,11 @@ config("default_warnings") {
         # TODO(thakis ): https://crbug.com/683349
         "-Wno-user-defined-warnings",
       ]
+
+      if (llvm_force_head_revision) {
+        # TODO(thakis): https://crbug.com/753973
+        cflags += [ "-Wno-enum-compare-switch" ]
+      }
     } else if (use_xcode_clang && xcode_version_int >= 830) {
       # This is necessary to allow a progressive transition from using xcode 8.0
       # to 8.3 or more recent. Remove when all bots are migrated to 8.3.