axTLS: allow "default" SSL version as well

When no explicit version is selected we should try to use whatever is
best for us, and in the axTLS case that means TLSv1.

lib/axtls.c

@@ -164,7 +164,12 @@ Curl_axtls_connect(struct connectdata *conn,
     return CURLE_OK;
 
   /* axTLS only supports TLSv1 */
-  if(data->set.ssl.version != CURL_SSLVERSION_TLSv1) {
+  /* check to see if we've been told to use an explicit SSL/TLS version */
+  switch(data->set.ssl.version) {
+  case CURL_SSLVERSION_DEFAULT:
+  case CURL_SSLVERSION_TLSv1:
+    break;
+  default:
     failf(data, "axTLS only supports TLSv1");
     return CURLE_SSL_CONNECT_ERROR;
   }