A follow-up change will add a CRYPTO_BUFFER variant. This makes the
naming match the header and doesn't require including x509.h. (Though
like ssl.h and pkcs8.h, some of the functions are implemented with code
that depends on crypto/x509.)

Change-Id: I5a7de209f4f775fe0027893f711326d89699ca1f
Reviewed-on: https://boringssl-review.googlesource.com/15128
Commit-Queue: Steven Valdez <svaldez@google.com>
Reviewed-by: Steven Valdez <svaldez@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>