glibc: properly handle internal addons

Some addons are bundled with glibc/eglibc, so we should not try to
download and extract them.

This is done as thus:
- at download time:
- if the add-on download fails, keep going;
- at extract time:
- if the addon is present in the source tree, ignore it;
- if the addon is missing in the source tree:
- if the archive is present, extract it;
- if the archive is missing, bail out.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# 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_start_files() {

    :

}

do_libc() {

    :

}

do_libc_finish() {

    :

}