shell: Add default case to switch statements

... to shut up a compiler warning.

src/shell-app-system.c

@@ -348,6 +348,9 @@ _shell_app_system_notify_app_state_changed (ShellAppSystem *self,
     case SHELL_APP_STATE_STOPPED:
       g_hash_table_remove (self->priv->running_apps, app);
       break;
+    default:
+      g_warn_if_reached();
+      break;
     }
   g_signal_emit (self, signals[APP_STATE_CHANGED], 0, app);
 }

src/shell-app.c

@@ -491,6 +491,9 @@ shell_app_activate_full (ShellApp      *app,
       case SHELL_APP_STATE_RUNNING:
         shell_app_activate_window (app, NULL, timestamp);
         break;
+      default:
+        g_assert_not_reached();
+        break;
     }
 }
 

src/shell-perf-log.c

@@ -672,6 +672,9 @@ shell_perf_log_collect_statistics (ShellPerfLog *perf_log)
               statistic->recorded = TRUE;
             }
           break;
+        default:
+          g_warning ("Unsupported signature in event");
+          break;
         }
     }