lib/replace: apply readline -Wstrict-prototypes workaround

lib/replace: apply readline -Wstrict-prototypes workaround

clang -Wstrict-prototypes has issues with readline > 6.3.
Fix suggested by Timur I. Bakeyev <timur@freebsd.org>

cf. https://lists.gnu.org/archive/html/bug-readline/2014-04/msg00018.html
cf. https://lists.samba.org/archive/samba-technical/2017-November/123923.html

Signed-off-by: Uri Simchoni <uri@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Nov 24 05:16:10 CET 2017 on sn-devel-144