ECC code.

Change-Id: I1a960620edbb30e10dcbab0e8053a1deb9db3262
Reviewed-on: https://boringssl-review.googlesource.com/3402
Reviewed-by: Adam Langley <agl@google.com>

According to rfc5480 and rfc4492 the hybrid format is not allowed
neither in certificates or the tls protocol.

Change-Id: I1d3fb5bef765bc7b58d29bdd60e15247fac4dc7a
Reviewed-on: https://boringssl-review.googlesource.com/2510
Reviewed-by: Adam Langley <agl@google.com>

Saves doing it ad-hoc all the time.

Change-Id: Ic1a1180f56eec37c19799649bb8f18237bd617f8
Reviewed-on: https://boringssl-review.googlesource.com/2241
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)