xplayer: Fix GCC 14 build

bacon-video-widget.c:1926:46: error: assignment to 'GstElement *' {aka 'struct _GstElement *'}
from incompatible pointer type 'GstObject *' {aka 'struct _GstObject *'} []

pkgs/by-name/xp/xplayer/package.nix

···
     patchPythonScript $out/lib/xplayer/plugins/dbus/dbusservice.py
   '';
 
+  env = lib.optionalAttrs stdenv.cc.isGNU {
+    NIX_CFLAGS_COMPILE = toString [
+      "-Wno-error=incompatible-pointer-types"
+      "-Wno-error=return-mismatch"
+    ];
+  };
+
   meta = with lib; {
     description = "Generic media player from Linux Mint";
     license = with licenses; [