LU-9859 libcfs: handle missing refcount.h

LU-9859 libcfs: handle missing refcount.h

Recently the OpenSFS tree was modified to make backported headers to
appear like native Linux kernel headers to avoid ifdef handling. One
missed is refcount.h. Rename linux-refcount.h to refcount.h to make
it look like the native kernel version. Change EXTRA_KCFLAGS to not
include the Lustre include directories since it contains the fake
kernel headers in the autoconf test. Also remove stray
LC_REPLACE_EXCEPTIONAL_ENTRIES.

Change-Id: Ia5de6dab0837db419a6b02b3b2a6ddeb6bb62f03
Test-Parameters: trivial
Fixes: 742897a967cf ("LU-13274 uapi: make lnet UAPI headers C99 compliant")
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38390
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>