Ignore genperf lib in merge_libs.py.
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: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9606}

TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc