libstdc++: Format chrono %a/%A/%b/%h/%B/%p using locale's time_put [PR117214]

libstdc++: Format chrono %a/%A/%b/%h/%B/%p using locale's time_put [PR117214]

C++ formatting locale could have a custom time_put that performs
differently from the C locale, so do not use __timepunct directly,
instead all of above specifiers use _M_locale_fmt.

For %a/%A/%b/%h/%B, the code handling the exception is now moved
to the _M_check_ok function, that is invoked before handling of the
conversion specifier. For time_points the values of months/weekday
are computed, and thus are always ok(), this information is indicated
by new _M_time_point member of the _ChronoSpec.

The different behavior of j specifier for durations and time_points/calendar
types, is now handled using only _ChronoParts, and _M_time_only in _ChronoSpec
is no longer needed, thus it was removed.

	PR libstdc++/117214

libstdc++-v3/ChangeLog:

	* include/bits/chrono_io.h (_ChronoSpec::_M_time_only): Remove.
	(_ChronoSpec::_M_time_point): Define.
	(__formatter_chrono::_M_parse): Use __parts to determine
	interpretation of j.
	(__formatter_chrono::_M_check_ok): Define.
	(__formatter_chrono::_M_format_to): Invoke _M_check_ok.
	(__formatter_chrono::_M_a_A, __formatter_chrono::_M_b_B): Move
	exception throwing to _M_check_ok.
	(__formatter_chrono::_M_j): Use _M_needs to define interpretation.
	(__formatter_duration::_S_spec_for): Set _M_time_point.
	* testsuite/std/time/format/format.cc: Test for exception for !ok()
	months/weekday.
	* testsuite/std/time/format/pr117214_custom_timeput.cc: New
	test.

Co-authored-by: Tomasz Kaminski <tkaminsk@redhat.com>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: XU Kailiang <xu2k3l4@outlook.com>
Signed-off-by: Tomasz Kaminski <tkaminsk@redhat.com>