Unexport and prune EVP_MD_CTX flags.

The only flag is EVP_MD_CTX_FLAG_NO_INIT and no good can possibly come of
anyone outside EVP_PKEY_HMAC calling it. (And indeed no one calls it.
EVP_MD_CTX_set_flags has a caller in wpa_supplicant, but it uses
EVP_MD_CTX_FLAG_NON_FIPS_ALLOW which we don't define. The call is guarded by a
pair of ifdefs for some FIPS mode wpa_supplicant.)

Change-Id: I70ab8ffa646f3f75dfa4d37c96b9e82448ff1e40
Reviewed-on: https://boringssl-review.googlesource.com/4971
Reviewed-by: Adam Langley <agl@google.com>
4 files changed