util.c: fix _WIN32 port of strptime

In _WIN32 builds, TIME_MAX needs to be INT32_MAX.

Also fix UB overflow, and useless check in NetBSD's strptime:
    (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 9999999999 as a valid
timestamp, equivalent to  1410065398  (Sat 20 Nov 17:46:39 UTC)
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.

Author: emanuele6

src/util.c

@@ -819,11 +819,16 @@ again:		switch (c = *fmt++) {
             continue;
 
 #ifndef TIME_MAX
+#ifdef _WIN32
+#define TIME_MAX	INT32_MAX
+#else
 #define TIME_MAX	INT64_MAX
+#endif
 #endif
         case 's':	/* seconds since the epoch */
             {
-                time_t sse = 0;
+                time_t tsse;
+                uint64_t sse = 0;
                 uint64_t rulim = TIME_MAX;
 
                 if (*bp < '0' || *bp > '9') {
@@ -838,14 +843,16 @@ again:		switch (c = *fmt++) {
                 } while ((sse * 10 <= TIME_MAX) &&
                      rulim && *bp >= '0' && *bp <= '9');
 
-                if (sse < 0 || (uint64_t)sse > TIME_MAX) {
+                if (sse > TIME_MAX) {
                     bp = NULL;
                     continue;
                 }
+
+                tsse = sse;
 #ifdef _WIN32
-                if (localtime_s(tm, &sse) == 0)
+                if (localtime_s(tm, &tsse) == 0)
 #else
-                if (localtime_r(&sse, tm))
+                if (localtime_r(&tsse, tm))
 #endif
                     state |= S_YDAY | S_WDAY | S_MON | S_MDAY | S_YEAR;
                 else