scripts/populate: add option to use an alternate sysroot

Add a new command line option, "-r", which allows the user to specify
an alternate sysroot location to copy libraries from. This is useful
when using the toolchain in combination with a separate root filesystem,
or when working with multiple different root filesystems.

Signed-off-by: Nate Case <ncase@xes-inc.com>

#!/bin/sh

SKIP_ME="### CT_NG SKIP ME ###"

skip_me=$(($(cat "${0}" |@@grep@@ --binary-files=text -o -b -E "^${SKIP_ME}$" |cut -d : -f 1)+${#SKIP_ME}+1))

dd if="${0}" bs=${skip_me} skip=1 2>/dev/null |bzcat

exit 0

### CT_NG SKIP ME ###