mariadb-binlog ignores a --stop-datetime of exactly the max timestamp on Windows

On Windows, 11.4 takes a --stop-datetime that converts to exactly TIMESTAMP_MAX_VALUE as if the option wasn't given at all:

mariadb-binlog --stop-datetime='2038-01-19 03:14:07' master-bin.000001    # in UTC

Linux prints "WARNING: Did not reach stop datetime '2038-01-19 03:14:07' before end of input", Windows prints nothing.

In 11.4 an unset stop_datetime is MY_TIME_T_MAX (LONG_MAX), checked with stop_datetime != MY_TIME_T_MAX. long is 32-bit on Windows, so LONG_MAX == INT_MAX32 == TIMESTAMP_MAX_VALUE, which is a valid timestamp.

11.5+ isn't affected, since MDEV-33239 replaced the magic value with a stop_datetime_given flag.

Since MDEV-40294, over-max values are clamped to TIMESTAMP_MAX_VALUE, so they hit this too. That's how it showed up in the Windows CI of PR #5983; its test works around it with --replace_regex for now.