Trim tls1_check_chain and CERT_PKEY flags.

Many are now unused. Only two are currently considered in cipher selection:
CERT_PKEY_VALID and CERT_PKEY_SIGN. (As per previous commits, this is either
bizarre due to limited slots or redundant with ssl_early_callback_ctx. We can
probably prune this too.)

This also fixes a bug where DTLS 1.0 went through a TLS 1.2 codepath. As the
DTLS code is currently arranged, all version comparisons must be done via
macros like SSL_USE_SIGALGS. (Probably we should add functions to map from DTLS
to TLS versions and slowly move the library to using the TLS version as
in-memory representation.)

Change-Id: I89bcf5b7b9ea5cdecf54f4445156586377328fe0
Reviewed-on: https://boringssl-review.googlesource.com/2286
Reviewed-by: Adam Langley <agl@google.com>
2 files changed