chan_iax2.c: Don't send unsanitized data to the logger.

This resolves an issue where non-printable characters could be sent to
the console/log files.

channels/iax2/parser.c

@@ -1063,7 +1063,7 @@ int iax_parse_ies(struct iax_ies *ies, unsigned char *data, int datalen)
 			if (len == (int)sizeof(unsigned int)) {
 				ies->calling_ani2 = ntohl(get_unaligned_uint32(data + 2));
 			} else {
-				snprintf(tmp, (int)sizeof(tmp), "callingani2 was %d long: %s\n", len, data + 2);
+				snprintf(tmp, sizeof(tmp), "Expected callingani2 to be %zu bytes but was %d\n", sizeof(unsigned int), len);
 				errorf(tmp);
 			}
 			break;