Fix build under GCC 8

src/cli_merge.cpp

@@ -331,7 +331,7 @@ struct snap_merger_t
             printf("\rOverwriting blocks: %lu/%lu\n", to_process, to_process);
         }
         // Done
-        result = { .text = "Done, layers from "+from_name+" to "+to_name+" merged into "+target_name };
+        result = (cli_result_t){ .text = "Done, layers from "+from_name+" to "+to_name+" merged into "+target_name };
         state = 100;
     resume_100:
         return;