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>

# This file adds functions to build the C library for bare metal (IE. none)

# Copyright 2008 Yann E. MORIN

# Licensed under the GPL v2. See COPYING in the root of this package

do_libc_get() {

    :

}

do_libc_extract() {

    :

}

do_libc_check_config() {

    :

}

do_libc_headers() {

    :

}

do_libc_start_files() {

    :

}

do_libc() {

    :

}

do_libc_finish() {

    :

}