meshlab: set QT_QPA_PLATFORM xcb (#306524)

pkgs/applications/graphics/meshlab/default.nix

···
     patchelf --add-needed $out/lib/meshlab/libmeshlab-common.so $out/bin/.meshlab-wrapped
   '';
 
+  # display a black screen on wayland, so force XWayland for now.
+  # Might be fixed when upstream will be ready for Qt6.
+  qtWrapperArgs = [
+    "--set QT_QPA_PLATFORM xcb"
+  ];
+
   meta = {
     description = "System for processing and editing 3D triangular meshes";
     mainProgram = "meshlab";