Add TSAN suppression for deadlocks in libGLX.so

This software isn't under our control, so suppress deadlock warnings we
can't fix.

BUG=691029

Review-Url: https://codereview.chromium.org/2807523002
Cr-Commit-Position: refs/heads/master@{#462960}

build/sanitizers/tsan_suppressions.cc

@@ -246,6 +246,9 @@ char kTSanDefaultSuppressions[] =
 "race:net::(anonymous namespace)::ProxyResolverV8TracingImpl::RequestImpl"
 "::~RequestImpl()\n"
 
+// http://crbug.com/691029
+"deadlock:libGLX.so*\n"
+
 // End of suppressions.
 ;  // Please keep this semicolon.