jumbo: utils-arm64.cc: undef __

Bug: chromium:746958
Change-Id: I5df144055d1918bf26acba648e07646150249d94
Reviewed-on: https://chromium-review.googlesource.com/647549Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@opera.com>
Cr-Commit-Position: refs/heads/master@{#47782}

src/arm64/utils-arm64.cc

@@ -132,6 +132,7 @@ int MaskToBit(uint64_t mask) {
   return CountTrailingZeros(mask, 64);
 }
 
+#undef __
 
 }  // namespace internal
 }  // namespace v8