Update-Note: There's some chance this'll break iOS since I was unable to
test it there. The iPad I have to test on is too new to run 32-bit code
at all.

Change-Id: I6593f91b67a5e8a82828237d3b69ed948b07922d
Reviewed-on: https://boringssl-review.googlesource.com/c/34725
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>