This is no longer necessary now that we use mac_toolchain.py.

Bug: angleproject:5114
Change-Id: I0afac641d55e9be2bd04103301aec3080d3332c8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2823859Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>