Remove lsan suppression.txt

After https://codereview.chromium.org/941433004/
the buildbots are no longer specifying this file as the LSan
suppressions from the command line.
In https://code.google.com/p/webrtc/source/detail?r=8406
we added compiler-based suppressions for WebRTC to be used
as default.

R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/36349004

Cr-Commit-Position: refs/heads/master@{#8512}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8512 4adac7df-926f-26a2-2b94-8c16560cd09d
3 files changed