BUG=129

Change-Id: I4a501fa620b7b5b4c585731ec1ece94407e9b727
Reviewed-on: https://boringssl-review.googlesource.com/16510
Reviewed-by: Adam Langley <agl@google.com>

Most C standard library functions are undefined if passed NULL, even
when the corresponding length is zero. This gives them (and, in turn,
all functions which call them) surprising behavior on empty arrays.
Some compilers will miscompile code due to this rule. See also
https://www.imperialviolet.org/2016/06/26/nonnull.html

Add OPENSSL_memcpy, etc., wrappers which avoid this problem.

BUG=23

Change-Id: I95f42b23e92945af0e681264fffaf578e7f8465e
Reviewed-on: https://boringssl-review.googlesource.com/12928
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

Change-Id: I0aab9c94fcfa58b9cd46eaf716d9317f532f79a2
Reviewed-on: https://boringssl-review.googlesource.com/11850
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: Steven Valdez <svaldez@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>