Tagging non-pointer return types const doesn't do anything and makes
some compilers grumpy. Thanks to Daniel Hirche for the report.

Change-Id: I157ddefd8f7e604b4d8317ffa2caddb8f0dd89de
Reviewed-on: https://boringssl-review.googlesource.com/11849
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

These structures allow for blobs of data (e.g. certificates) to be
deduplicated in memory.

Change-Id: Iebfec90b85d55565848a178b6951562b4ccc083e
Reviewed-on: https://boringssl-review.googlesource.com/11820
Reviewed-by: Adam Langley <alangley@gmail.com>
Commit-Queue: Adam Langley <alangley@gmail.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>