CCBC-1599: account NUL-byte when format IPv6 address

Change-Id: I9f0a0f350019def8cc5f7a9734ab724135d519d2
Reviewed-on: https://review.couchbase.org/c/libcouchbase/+/192095
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Jared Casey <jared.casey@couchbase.com>

Author: avsej

src/vbucket/vbucket.c

@@ -804,7 +804,7 @@ void lcbvb_replace_host(lcbvb_CONFIG *cfg, const char *hoststr)
     char *replacement = (char *)hoststr;
     if (strchr(replacement, ':')) {
         size_t len = strlen(hoststr);
-        replacement = calloc(len + 2, sizeof(char));
+        replacement = calloc(len + 3 /* '[', ']', '\0' */, sizeof(char));
         replacement[0] = '[';
         memcpy(replacement + 1, hoststr, len);
         replacement[len + 1] = ']';