util.c: fix _WIN32 port of strptime

[emanuele6]

In _WIN32 builds, TIME_MAX needs to be INT32_MAX.

Also fix UB overflow, and useless check in NetBSD's strptime("%s"):

(time_t_value * 10) <= TIME_MAX

is always true since time_t is signed, and TIME_MAX is its maximum value.

And, if it is not optimised out, it causes a signed integer overflow (undefined in standard C) for inputs that start with a sequence of characters between "922337203685477581" and "999999999999999999" (inclusive, 64-bit time_t).

Also, since the check does not do what it is supposed to do, even if we assume that signed integer overflow is defined like for unsigned integers, on builds where time_t is int32_t, and TIME_MAX is INT32_MAX, this will cause strptime("%s") to accept 99999999999 as a valid timestamp, equivalent to 1410065398 (Sun 7 Sep 04:49:58 UTC 2014) instead of rejecting it.
This works because floor(log10(UINT32_MAX)) == floor(log10(INT32_MAX)) in 32-bit.

Noticed thanks to a compiler warning in the windows build CI.

[emanuele6]

Now, jq/libjq builds without warnings on the windows CI job

[wader]

This was sent upstream as https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=58041 or? wait for that before merge?

[emanuele6]

This was fixed in NetBSD rewriting the loop in a different way; I could port the NetBSD fix to jq instead of using mine.

[wader]

This was fixed in NetBSD rewriting the loop in a different way; I could port the NetBSD fix to jq instead of using mine.

Ok, if equivalent fix i think using the netbsd version will be less confusing, thinking if there will be backports in the future etc

[emanuele6]

The NetBSD code triggers another warning:

ake[2]: Entering directory '/d/a/jq/jq'
  CC       src/jv_dtoa_tsd.lo
  CC       src/lexer.lo
  CC       src/parser.lo
  GEN      jq.1
  CC       src/main.o
  CC       src/builtin.lo
  CC       src/bytecode.lo
  CC       src/compile.lo
  CC       src/execute.lo
  CC       src/jq_test.lo
  CC       src/jv.lo
  CC       src/jv_alloc.lo
  CC       src/jv_aux.lo
  CC       src/jv_dtoa.lo
  CC       src/jv_file.lo
  CC       src/jv_parse.lo
  CC       src/jv_print.lo
  CC       src/jv_unicode.lo
  CC       src/linker.lo
  CC       src/locfile.lo
  CC       src/util.lo
  CC       src/decNumber/decContext.lo
  CC       src/decNumber/decNumber.lo
src/util.c: In function 'strptime':
src/util.c:843:25: warning: comparison of integer expressions of different signedness: 'time_t' {aka 'long int'} and 'long unsigned int' [-Wsign-compare]
  843 |                 if (sse > TIME_MAX - d) {
      |                         ^
  CCLD     libjq.la
  CCLD     jq.exe
make[2]: Leaving directory '/d/a/jq/jq'
make[1]: Leaving directory '/d/a/jq/jq'

[wader]

The NetBSD code triggers another warning:

the joy! 🥳