Use bash binary from env instead of /bin/bash for scripts

It's not possible to run any of the scripts on distributions which do
have `bash` not in `/bin`. This is being fixed by using `/usr/bin/env
bash` instead.

Signed-off-by: Sascha Grunert <sgrunert@suse.com>

hack/check_root.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 if ! [ $(id -u) = 0 ]; then
    echo "Please run as root! '$@' requires root privileges."
    exit 1