Bug 1729082 - Stop leaking the portal Pipewire file descriptor, r=emilio

It is used to create the `pw_core` object that is disconnected above.

Differential Revision: https://phabricator.services.mozilla.com/D124508

third_party/libwebrtc/webrtc/modules/desktop_capture/linux/base_capturer_pipewire.cc

@@ -238,6 +238,10 @@ BaseCapturerPipeWire::~BaseCapturerPipeWire() {
     g_object_unref(proxy_);
     proxy_ = nullptr;
   }
+
+  if (pw_fd_ != -1) {
+    close(pw_fd_);
+  }
 }
 
 void BaseCapturerPipeWire::InitPortal() {