Often build systems will use -shared when creating shared libraries, so

Often build systems will use -shared when creating shared libraries, so
don't barf on the flag when we see it.  This makes porting efforts easier.
As a sanity check, make sure we see the -shared-lib-id flag when creating
a shared library.

Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>