Prefer C99 formats like %jd to doing it by hand

Prefer C99 formats like %jd to doing it by hand

It’s now safe to assume support for C99 formats like %jd, so remove
some of the longwinded formatting code put in only to be portable to
pre-C99 platforms.
* gnulib.modules: Add intprops.
* src/buffer.c (format_total_stats, try_new_volume)
(write_volume_label):
* src/checkpoint.c (format_checkpoint_string):
* src/compare.c (verify_volume):
* src/create.c (to_chars_subst, dump_regular_file):
* src/incremen.c (read_num):
* src/list.c (read_and, from_header, simple_print_header)
(print_for_mkdir):
* src/sparse.c (sparse_dump_region):
* src/system.c (dec_to_env, sys_exec_info_script)
(sys_exec_checkpoint_script):
* src/xheader.c (out_of_range_header):
Prefer C99 formats like %jd and %ju to STRINGIFY_BIGINT.
* src/common.h: Sort includes.
Include intprops.h, verify.h.  All other includes of verify.h
removed.
(intmax, uintmax): New functions and macros.
(STRINGIFY_BIGINT): Remove; no longer used.
(TIMESPEC_STRSIZE_BOUND): Make it 1 byte bigger, for negatives.
* src/create.c (MAX_VAL_WITH_DIGITS, to_base256):
Use *_WIDTH macros rather than assuming no padding bits.
Prefer UINTMAX_MAX to (uintmax_t) -1.
* src/list.c (tartime): Use strftime result rather
than running strlen later.
* src/misc.c (timetostr): New function.  Prefer it when
printing time_t values.