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.

src/misc.c

@@ -372,7 +372,7 @@ replace_prefix (char **pname, const char *samp, size_t slen,
 /* Handling numbers.  */
 
 /* Convert VALUE, which is converted from a system integer type whose
-   minimum value is MINVAL and maximum MINVAL, to an decimal
+   minimum value is MINVAL and maximum MINVAL, to a decimal
    integer string.  Use the storage in BUF and return a pointer to the
    converted string.  If VALUE is converted from a negative integer in
    the range MINVAL .. -1, represent it with a string representation
@@ -392,6 +392,14 @@ sysinttostr (uintmax_t value, intmax_t minval, uintmax_t maxval,
     }
 }
 
+/* Convert T to a decimal integer string.  Use the storage in BUF and
+   return a pointer to the converted string.  */
+char *
+timetostr (time_t t, char buf[SYSINT_BUFSIZE])
+{
+  return sysinttostr (t, TYPE_MINIMUM (time_t), TYPE_MAXIMUM (time_t), buf);
+}
+
 /* Convert a prefix of the string ARG to a system integer type whose
    minimum value is MINVAL and maximum MAXVAL.  If MINVAL is negative,
    negative integers MINVAL .. -1 are assumed to be represented using
@@ -472,11 +480,10 @@ code_ns_fraction (int ns, char *p)
 }
 
 char const *
-code_timespec (struct timespec t, char sbuf[TIMESPEC_STRSIZE_BOUND])
+code_timespec (struct timespec t, char tsbuf[TIMESPEC_STRSIZE_BOUND])
 {
   time_t s = t.tv_sec;
   int ns = t.tv_nsec;
-  char *np;
   bool negative = s < 0;
 
   /* ignore invalid values of ns */
@@ -489,11 +496,12 @@ code_timespec (struct timespec t, char sbuf[TIMESPEC_STRSIZE_BOUND])
       ns = BILLION - ns;
     }
 
-  np = umaxtostr (negative ? - (uintmax_t) s : (uintmax_t) s, sbuf + 1);
-  if (negative)
-    *--np = '-';
-  code_ns_fraction (ns, sbuf + UINTMAX_STRSIZE_BOUND);
-  return np;
+  bool minus_zero = negative & !s;
+  char *sstr = timetostr (s, tsbuf + 1);
+  sstr[-1] = '-';
+  sstr -= minus_zero;
+  code_ns_fraction (ns, sstr + strlen (sstr));
+  return sstr;
 }
 
 struct timespec