Move iOS only toolchain-related scripts into build/config/ios.

This CL is a refactor with no intended behavior change.

Bug: 965663
Change-Id: I07a61658d730c0982e52f7e496d05cb274c9ef2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648695
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#667184}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7479370d8d92077c27d77434ace959a331ce1182
3 files changed