allow_posix_link_time_opt and is_cfi are clang features

This is required for GCC builds with is_official_build=true.

BUG=464797

Review-Url: https://codereview.chromium.org/2858723002
Cr-Original-Commit-Position: refs/heads/master@{#469188}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 9dd38d20453e05cecaa0f883f0865da3837a380c
1 file changed