DrMemory: Removing suppression as Dr Memory was fixed.

According to
https://code.google.com/p/webrtc/issues/detail?id=3275
the issue is now fixed in the drmemory.DEPS of r267732.
Since we don't roll this DEPS (it's automatically updated
as it's a separate solution in the checkout for these bots)
we already have this update.

BUG=3275
TEST=Passing trybot: git try --bot=win_drmemory_light
R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/20429004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6077 4adac7df-926f-26a2-2b94-8c16560cd09d