This change imports sha256-armv4.pl from upstream at rev 8d1ebff4. This
includes changes to remove the use of adrl, which is not supported by
Clang.

Change-Id: I429e7051d63b59acad21601e40883fc3bd8dd2f5
Reviewed-on: https://boringssl-review.googlesource.com/12480
Commit-Queue: Adam Langley <alangley@gmail.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>