BUG/MINOR: checks/server: use_ssl member must be signed

(cherry picked from commit 4a8c026117f2f19bd2f8f0ac64954c8a4f717bc8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

[Cf: Forgot to mention to backport it with the commit 8a5bf35ce
     ("BUG/MINOR: checks: Respect the no-check-ssl option")]

(cherry picked from commit f1dc6a462c30355f4d886d9c5e3af48477177e63)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
2 files changed