Add a comment about the bug being a WontFix

BUG=455638
TBR=thestig@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1468383002

Cr-Commit-Position: refs/heads/master@{#361321}

build/sanitizers/tsan_suppressions.cc

@@ -280,6 +280,7 @@ char kTSanDefaultSuppressions[] =
 // https://crbug.com/448203
 "race:blink::RemoteFrame::detach\n"
 
+// Lock inversion in third party code, won't fix.
 // https://crbug.com/455638
 "deadlock:dbus::Bus::ShutdownAndBlock\n"