BUG/MINOR: compression: Missing calloc return value check in comp_append_type/algo

BUG/MINOR: compression: Missing calloc return value check in comp_append_type/algo

A memory allocation failure happening in comp_append_type or
comp_append_algo called while parsing compression options would have
resulted in a crash. These functions are only called during
configuration parsing.

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

(cherry picked from commit 6443bcc2e1f2e1e11af76ef460d8241f06223de8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit a3a8d50d992ab145e5c353cc36e8a787d3aead57)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>