LibCore+flock: Make Core::System::waitpid more ergonomic

Author: https://github.com/juniorrantila
Commit: 0d328f3c86
Pull-request: https://github.com/SerenityOS/serenity/pull/11790
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/kleinesfilmroellchen ✅

Userland/Utilities/flock.cpp

@@ -19,7 +19,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     pid_t child_pid = TRY(Core::System::posix_spawnp(arguments.strings[2], nullptr, nullptr, &arguments.argv[2], environ));
-    int status = TRY(Core::System::waitpid(child_pid, &status, 0));
+    auto [_, status] = TRY(Core::System::waitpid(child_pid));
 
     return WEXITSTATUS(status);
 }