By using memcpy, GCC can already optimise things so that the compiled
code is identical on x86-64. Thus we don't need to worry about having
different versions for platforms with, and without, strict alignment.

(Thanks to Emil Mikulic.)

Change-Id: I08bc5fa9b67aa369be2dd2e29e4229fb5b5ff40c
Reviewed-on: https://boringssl-review.googlesource.com/10381
Commit-Queue: Adam Langley <agl@google.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>