libinput: don't try to create /etc in build

How libinput tries to create /etc changed in upstream commit
05501cd34f9c ("meson: use install_emptydir to create directory"),
so we have to update our sed expression.

This was missed in when libinput was updated in Nixpkgs due to a Nix
bug[1], which made the sandbox's /etc writeable.

[1]: NixOS/nix#7813

Fixes: bf928e5 ("libinput: 1.21.0 → 1.22.1")

pkgs/development/libraries/libinput/default.nix

@@ -113,8 +113,8 @@ stdenv.mkDerivation rec {
       test/check-leftover-udev-rules.sh \
       test/helper-copy-and-exec-from-tmp.sh
 
-    # Don't create an empty /etc directory.
-    sed -i "/install_subdir('libinput', install_dir : dir_etc)/d" meson.build
+    # Don't create an empty directory under /etc.
+    sed -i "/install_emptydir(dir_etc \/ 'libinput')/d" meson.build
   '';
 
   passthru = {