virtualbox: fix X11 shared clipboard (#370722)

pkgs/applications/virtualization/virtualbox/default.nix

@@ -14,6 +14,7 @@
   xorgproto,
   libXext,
   libXcursor,
+  libXfixes,
   libXmu,
   libIDL,
   SDL2,
@@ -204,6 +205,9 @@ stdenv.mkDerivation (finalAttrs: {
     grep 'libdbus-1\.so\.3'     src include -rI --files-with-match | xargs sed -i -e '
       s@"libdbus-1\.so\.3"@"${dbus.lib}/lib/libdbus-1.so.3"@g'
 
+    grep 'libXfixes\.so\.3'     src include -rI --files-with-match | xargs sed -i -e '
+      s@"libXfixes\.so\.3"@"${libXfixes.out}/lib/libXfixes.so.3"@g'
+
     grep 'libasound\.so\.2'     src include -rI --files-with-match | xargs sed -i -e '
       s@"libasound\.so\.2"@"${alsa-lib.out}/lib/libasound.so.2"@g'