To make it nicer and easily maintainable.

Also moving the check into fixdep sub make, so its output is not
scattered around the build output.

Removing extra $$ from mman*.h checks.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1481030331-31944-5-git-send-email-jolsa@kernel.org
[ Use /bin/sh, and 'function check() {' -> 'check () {' to make it work with busybox, in Alpine Linux, for instance ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>