s3: fix fcntl waf configure check

s3: fix fcntl waf configure check

RN: Fix fcntl waf configure check
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14503

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Mon Sep 21 07:26:54 UTC 2020 on sn-devel-184

(cherry picked from commit 454ccd986b61799908a6898a55d0480911f15306)

Autobuild-User(v4-13-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-13-test): Fri Feb 26 10:57:20 UTC 2021 on sn-devel-184