Don't send a hangup on user media failure

We won't have sent the invite anyway. Also termainate before we
fire the error event so the call is 'ended' when the event handlers
fire (which means if they try to hang up it's also ignored)

src/webrtc/call.js

@@ -767,6 +767,7 @@ MatrixCall.prototype._getLocalOfferFailed = function(error) {
  * @param {Object} error
  */
 MatrixCall.prototype._getUserMediaFailed = function(error) {
+    terminate(this, "local", 'user_media_failed', false);
     this.emit(
         "error",
         callError(
@@ -775,7 +776,6 @@ MatrixCall.prototype._getUserMediaFailed = function(error) {
             "does this app have permission?",
         ),
     );
-    this.hangup("user_media_failed");
 };
 
 /**