Roll Clang 325667:327688

Clang r326867 turned on SafeStack when targeting Fuchsia by default.
Turn it off in our build config until all the tests pass.

Bug: 817298, 821951

Change-Id: Id2d9f911eb62fe6823365baeba55a4ccc0b484ce
Reviewed-on: https://chromium-review.googlesource.com/959003
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#543745}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 6705a9b1d17e8f56c9a8229c971a7286ce1fbe42

config/fuchsia/BUILD.gn

@@ -55,5 +55,9 @@ config("compiler") {
     "-Wl,--as-needed",
   ]
 
+  # TODO(crbug.com/821951): Clang enables SafeStack by default when targeting
+  # Fuchsia, but it breaks some tests, notably in V8.
+  cflags += [ "-fno-sanitize=safe-stack" ]
+
   libs = [ "zircon" ]
 }