Suppress data races in libjingle_peerconnection_unittest

TBR=pbos@webrtc.org
BUG=4488
TESTED=Passing builds with:
out/Release/libjingle_peerconnection_unittest --gtest_filter=PeerConnectionInterfaceTest* --gtest_repeat=100 --gtest_break_on_failure
(reproduces without these suppressions)

Review URL: https://webrtc-codereview.appspot.com/50539004

Cr-Commit-Position: refs/heads/master@{#8886}
1 file changed