Add SSL_SESSION_{get,set}_protocol_version.

SSL_SESSION_set_protocol_version is useful when unit-testing a session
cache.

Change-Id: I4b04e31d61ce40739323248e3e5fdae498c4645e
Reviewed-on: https://boringssl-review.googlesource.com/21044
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>
diff --git a/ssl/t1_enc.cc b/ssl/t1_enc.cc
index 8f8d328..85c368c 100644
--- a/ssl/t1_enc.cc
+++ b/ssl/t1_enc.cc
@@ -462,7 +462,7 @@
                     SSL3_RANDOM_SIZE, ssl->s3->client_random, SSL3_RANDOM_SIZE);
   }
 
-  const EVP_MD *digest = SSL_SESSION_get_digest(session);
+  const EVP_MD *digest = ssl_session_get_digest(session);
   return tls1_prf(digest, out, out_len, session->master_key,
                   session->master_key_length, TLS_MD_KEY_EXPANSION_CONST,
                   TLS_MD_KEY_EXPANSION_CONST_SIZE, ssl->s3->server_random,
@@ -511,7 +511,7 @@
   }
 
   const SSL_SESSION *session = SSL_get_session(ssl);
-  const EVP_MD *digest = SSL_SESSION_get_digest(session);
+  const EVP_MD *digest = ssl_session_get_digest(session);
   int ret = tls1_prf(digest, out, out_len, session->master_key,
                      session->master_key_length, label, label_len, seed,
                      seed_len, NULL, 0);