Disable SHA256 if not supported.

ssl/ssl_ciph.c

diff --git a/ssl/ssl_ciph.c b/ssl/ssl_ciph.c
index 132b848..38d5977 100644
--- a/ssl/ssl_ciph.c
+++ b/ssl/ssl_ciph.c
@@ -709,6 +709,7 @@
 
 	*mac |= (ssl_digest_methods[SSL_MD_MD5_IDX ] == NULL) ? SSL_MD5 :0;
 	*mac |= (ssl_digest_methods[SSL_MD_SHA1_IDX] == NULL) ? SSL_SHA1:0;
+	*mac |= (ssl_digest_methods[SSL_MD_SHA256_IDX] == NULL) ? SSL_SHA256:0;
 	*mac |= (ssl_digest_methods[SSL_MD_GOST94_IDX] == NULL) ? SSL_GOST94:0;
 	*mac |= (ssl_digest_methods[SSL_MD_GOST89MAC_IDX] == NULL || ssl_mac_pkey_id[SSL_MD_GOST89MAC_IDX]==NID_undef)? SSL_GOST89MAC:0;