Fix some uses of int in list.c

Fix some uses of int in list.c

* src/list.c (decode_xform): Last arg is now int, not a void *
pointer to that int.  All uses changed.
(enforce_one_top_level): Don’t assume string length fits in int.
(transform_stat_info): Prefer char to int for typeflag.
All uses changed.
(decode_header): Prefer bool for booleans.  All uses changed.
(ugswidth): Now idx_t, not int, since in theory it could
exceed INT_MAX.  All uses changed.
(simple_print_header, print_for_mkdir): Don’t assume printf length
fits in int, and similarly for length of user or group name.
* src/transform.c (transform_name_fp): Last arg is now int, not void *.
All uses changed.