Use enc_flags when deciding protocol variations.

Use the enc_flags field to determine whether we should use explicit IV,
signature algorithms or SHA256 default PRF instead of hard coding which
versions support each requirement.

ssl/s3_lib.c

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index 2fe30d7..b92d879 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -4458,14 +4458,14 @@
 		}
 	return(ret);
 	}
-/* If we are using TLS v1.2 or later and default SHA1+MD5 algorithms switch
- * to new SHA256 PRF and handshake macs
+/* If we are using default SHA1+MD5 algorithms switch to new SHA256 PRF
+ * and handshake macs if required.
  */
 long ssl_get_algorithm2(SSL *s)
 	{
 	long alg2 = s->s3->tmp.new_cipher->algorithm2;
-	if (TLS1_get_version(s) >= TLS1_2_VERSION &&
-	    alg2 == (SSL_HANDSHAKE_MAC_DEFAULT|TLS1_PRF))
+	if (s->method->ssl3_enc->enc_flags & SSL_ENC_FLAG_SHA256_PRF
+	    && alg2 == (SSL_HANDSHAKE_MAC_DEFAULT|TLS1_PRF))
 		return SSL_HANDSHAKE_MAC_SHA256 | TLS1_PRF_SHA256;
 	return alg2;
 	}