LU-3953 build: fix AC_LANG_SOURCE autoconf warnings

LU-3953 build: fix AC_LANG_SOURCE autoconf warnings

This fixes several places where the autoconf rules generate the
following warning:

configure.ac:23: warning: AC_LANG_CONFTEST: no AC_LANG_SOURCE
call detected in body

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Change-Id: Ib6a54310853b1e9aa34155e8bec9aae410278f25
Reviewed-on: http://review.whamcloud.com/10158
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>