fix(niri): close the IPC socket fd once (ScopedFd owns it), not twice

IPC::send() wrapped the socket fd in a util::ScopedFd, which closes the
fd in its destructor. The input stream was created with close_fd=true,
so the stream also closed the same fd, resulting in a double-close. In
multithreaded Waybar another thread can open a new fd with the same
number between the two close() calls, which the second close() then
wrongly closes. Pass close_fd=false so ScopedFd is the sole owner and
the fd is closed exactly once. The streams are declared after socketfd,
so they flush and destruct while the fd is still open, then ScopedFd
closes it.

src/modules/niri/backend.cpp

@@ -285,7 +285,7 @@ void IPC::unregisterForIPC(EventHandler* ev_handler) {
 Json::Value IPC::send(const Json::Value& request) {
   util::ScopedFd socketfd(connectToSocket());
 
-  auto unix_istream = Gio::UnixInputStream::create(socketfd, true);
+  auto unix_istream = Gio::UnixInputStream::create(socketfd, false);
   auto unix_ostream = Gio::UnixOutputStream::create(socketfd, false);
   auto istream = Gio::DataInputStream::create(unix_istream);
   auto ostream = Gio::DataOutputStream::create(unix_ostream);