BUG/MINOR: peers: Missing calloc return value check in peers_register_table

BUG/MINOR: peers: Missing calloc return value check in peers_register_table

A memory allocation failure happening during peers_register_table would
have resulted in a crash. This function is only called during init.

It was raised in GitHub issue #1233.
It could be backported to all stable branches.

(cherry picked from commit 208ff01b23eda19fe41780310f4d08ca86e28766)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit be5b1bb8cb683290f80856a3728ccaf3ad47b44b)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>