Ignore genperf lib in merge_libs.py.

It's built as a part of the chromium build(?), but causes problems with XCode 7's new bitcode intermediate format. It should really never been included, but it never caused link failures before.

BUG=

Review URL: https://codereview.webrtc.org/1236383002

Cr-Commit-Position: refs/heads/master@{#9606}
1 file changed