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_run

@@ -1,15 +1,2 @@
 #!/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" | dmenu "$@"
-	else
-		dmenu "$@" < "$cache"
-	fi
-) | ${SHELL:-"/bin/sh"} &
+dmenu_path | dmenu "$@" | ${SHELL:-"/bin/sh"} &