mpc: update to 0.33

Small Makefile cleanups.

Ran script through shellcheck.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
(cherry picked from commit 4fba03d6d1)

sound/mpc/files/pls-handler.sh

@@ -1,5 +1,5 @@
-#!/usr/bin/env sh
+#!/bin/sh
 echo parameter: file.pls
 mpc clear
-grep '^File[0-9]*' $1 | sed -e 's/^File[0-9]*=//' | mpc add
-mpc play
+grep '^File[0-9]*' "$1" | sed -e 's/^File[0-9]*=//' | mpc add
+mpc play