Fix memory issues reported by clang static analyzer (#7)

* Fix use after free in error path

Memory pointed by 'handle' is used in error path but it is freed before jumping to interface_failed. Remove the wrong free. Memory pointed by 'handle' gets freed in the error handling path.

* Free 'bus' when dbus_bus_get_private fails

If dbus_bus_get_private fails memory pointed by 'bus' is never freed. Free it.

* Free 'impl' if dbus_bus_get_private fails

When dbus_bus_get_private fails the memory pointed by 'impl' is not freed. Free it.

src/modules/module-flatpak.c

@@ -778,6 +778,7 @@ static bool module_init(struct pw_module *module, struct pw_properties *properti
 	return true;
 
       error:
+	free(impl);
 	pw_log_error("Failed to connect to system bus: %s", error.message);
 	dbus_error_free(&error);
 	return false;

src/modules/spa/spa-monitor.c

@@ -272,7 +272,6 @@ struct pw_spa_monitor *pw_spa_monitor_load(struct pw_core *core,
 		goto init_failed;
 	}
 	if ((res = spa_handle_get_interface(handle, t->spa_monitor, &iface)) < 0) {
-		free(handle);
 		pw_log_error("can't get MONITOR interface: %d", res);
 		goto interface_failed;
 	}

src/pipewire/rtkit.c

@@ -77,6 +77,7 @@ struct pw_rtkit_bus *pw_rtkit_bus_get_system(void)
 	return bus;
 
       error:
+	free(bus);
 	pw_log_error("Failed to connect to system bus: %s", error.message);
 	dbus_error_free(&error);
 	return NULL;