rust-common.bbclass: move musl-specific linking fix from rust-source.inc

This needs to be done for any item that is linked under rustc,
and not just rust itself. Latest python-cryptography exposes the issue.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit d3811228)
Signed-off-by: Steve Sakoman <steve@sakoman.com>