Add AES Key Wrap mode.

This is needed in order to support Web Crypto.

https://code.google.com/p/chromium/issues/detail?id=396407

Change-Id: I900d8cad2716c2e3341eeae153659502326c9173
Reviewed-on: https://boringssl-review.googlesource.com/1335
Reviewed-by: Adam Langley <agl@google.com>
8 files changed