Changes

configure: disable sys/sysctl.h on Linux
It generates deprecation warnings since glibc 2.29 and we don't need it
anyway.
Thanks to Pavan Balaji for the report.
Refs #384
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
(cherry picked from commit bf9ef3689e80aba3c8e6688cfbf3950a914358e5)