The build toolchain now requires xcode 10, so we have to roll.
Bug: None
Change-Id: Iafec62e7927ca8a81117710d09e2c42bcf18c0d1
Reviewed-on: https://webrtc-review.googlesource.com/97060
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24510}