modutils: support finit_module syscall

modutils: support finit_module syscall

On some systems like Chromium OS, loading modules from non-verified
filesystems is denied.  Only finit_module is allowed because an open
fd is passed which can be checked against a verified location.

Change the module loading code to first attempt finit_module and if
that fails for whatever reason, fall back to the existing logic.

On x86_64, this adds ~80 bytes to modutils/modutils.o and ~68 bytes
to modutils/modprobe-small.o.

Signed-off-by: Mike Frysinger <vapier@chromium.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>