typo fix in alloc-srvx.c; avoid dereferencing free()'d bans

src/alloc-srvx.c (srvx_realloc): Fix argument list to srvx_free().

src/chanserv.c (find_matching_bans): Make temporary copies of bans to
be removed.  Double-check remove count at end of loop.
(unban_user, cmd_open): Free the string copies.
(cmd_unbanall): Make temporary copies of removed bans and free them.
(handle_mode): Likewise.

src/opserv.c (cmd_clearbans): Likewise.
git-archimport-id: srvx@srvx.net--2005-srvx/srvx--devo--1.3--patch-8