musl doesn't provide argp, so we need argp-standalone, as we do for uclibc.
Rather than passing in -largp via the recipe, patch the configure script to
provide an argument for the libargp usage and check for it when needed, and
use PACKAGECONFIG. The initial patch to check for libargp and use it if
available came from Gentoo. The patches are kept separate despite the second
modifying what the first does, in order to keep the history/origin clear.
Signed-off-by: Christopher Larson <chris_larson@mentor.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
