dmenu_run: Split cache logic to dmenu_path again

This allows to run dmenu_path to update the cache using
a packager manager hook system

dmenu_path

@@ -0,0 +1,13 @@
+#!/bin/sh
+cachedir=${XDG_CACHE_HOME:-"$HOME/.cache"}
+if [ -d "$cachedir" ]; then
+	cache=$cachedir/dmenu_run
+else
+	cache=$HOME/.dmenu_cache # if no xdg dir, fall back to dotfile in ~
+fi
+IFS=:
+if stest -dqr -n "$cache" $PATH; then
+	stest -flx $PATH | sort -u | tee "$cache"
+else
+	cat "$cache"
+fi