Fuchsia/Zircon recently added support for exposing arm64 CPU features;
this CL uses the new system call to set OPENSSL_armcap_P.
Change-Id: I045dc0b58117afe6dae315a82bf9acfd8d99be1a
Reviewed-on: https://boringssl-review.googlesource.com/25865
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
