elf: Do not fail for failed dlmopen on audit modules (BZ #28061)

The dl_main sets the LM_ID_BASE to RT_ADD just before starting to
add load new shared objects.  The state is set to RT_CONSISTENT just
after all objects are loaded.

However if a audit modules tries to dlmopen an inexistent module,
the _dl_open will assert that the namespace is in an inconsistent
state.

This is different than dlopen, since first it will not use
LM_ID_BASE and second _dl_map_object_from_fd is the sole responsible
to set and reset the r_state value.

So the assert on _dl_open can not really be seen if the state is
consistent, since _dt_main resets it.  This patch removes the assert.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
(cherry picked from commit 484e672d)

Resolved conflicts:
	elf/Makefile
	elf/dl-open.c