evapi: minor fix in tag length compare

It was assigning the length instead of comparing it.

src/modules/evapi/evapi_dispatch.c

@@ -289,7 +289,7 @@ int evapi_dispatch_notify(evapi_msg_t *emsg)
 	n = 0;
 	for(i=0; i<EVAPI_MAX_CLIENTS; i++) {
 		if(_evapi_clients[i].connected==1 && _evapi_clients[i].sock>=0) {
-			if(emsg->tag.s==NULL || (emsg->tag.len = _evapi_clients[i].stag.len
+			if(emsg->tag.s==NULL || (emsg->tag.len == _evapi_clients[i].stag.len
 						&& strncmp(_evapi_clients[i].stag.s,
 									emsg->tag.s, emsg->tag.len)==0)) {
 				wlen = write(_evapi_clients[i].sock, emsg->data.s,