Fix CFI crashes when using dav1d for AV1 decoding.

Turns out that clang doesn't like LTO + mstack-alignment, so disable
alignment changes when use_thin_lto is true.

BUG=928743
R=liberato

Change-Id: Ibc2fb84acb515956c4bd1564c39728e0ecbc7801
Reviewed-on: https://chromium-review.googlesource.com/c/1455463
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629390}
11 files changed