meson: use install_emptydir() and drop meson-make-symlink.sh

The script is mostly equivalent to 'mkdir -p' and 'ln -sfr'.
Let's replace it with install_emptydir() builtin function and
inline meson call.

tmpfiles.d/meson.build

@@ -54,6 +54,5 @@ foreach pair : in_files
 endforeach
 
 if enable_tmpfiles and install_sysconfdir
-        meson.add_install_script(
-                'sh', '-c', mkdir_p.format(sysconfdir / 'tmpfiles.d'))
+        install_emptydir(sysconfdir / 'tmpfiles.d')
 endif