shadow: link executables statically for -native variant

shadow: link executables statically for -native variant

shadow 4.14.x adds a number of libraries it dynamically links with
(md, bsd, attr). This causes troubles in setscene tasks where
shadow executables are used (such as useradd), as pulling in
the needed dynamic libraries needs unpleasant special-casing.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>