libstdc++: Rewrite std::counting_semaphore base class [PR118494]

libstdc++: Rewrite std::counting_semaphore base class [PR118494]

Remove __platform_semaphore. Replace __atomic_semaphore with
__semaphore_base<bool> and change its counter to be ptrdiff_t when the
count doesn't fit in __platform_wait_t (PR 118494).

Make the std::counting_semaphore constructor constexpr to support
constant initialization (PR 110854).

Add precondition checks to the constructor and release member functions
(PR 98749).

libstdc++-v3/ChangeLog:

	PR libstdc++/118494
	PR libstdc++/110854
	PR libstdc++/98749
	* acinclude.m4 (GLIBCXX_CHECK_GTHREADS): Remove checks for
	sem_timedwait. Do not define _GLIBCXX_HAVE_POSIX_SEMAPHORE.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* include/bits/semaphore_base.h (__platform_semaphore): Remove.
	(__atomic_semaphore): Replace with __semaphore_base<bool> and
	make type of _M_count depend on template parameter. Fix _S_max
	constant to use correct type.
	(__semaphore_base::_M_try_acquire): Qualify to avoid ADL.
	(__semaphore_base::_M_release): Return old value. Remove FIXME
	comment.
	(__semaphore_impl): Replace typedef with alias template.
	* include/bits/version.def (semaphore): Do not depend on
	_GLIBCXX_HAVE_POSIX_SEMAPHORE.
	* include/bits/version.h: Regenerate.
	* include/std/semaphore (semaphore): Adjust type of _M_sem
	member. Add constexpr to constructor. Add assertions to
	(semaphore::semaphore(ptrdiff_t)): Add constexpr. Add assertion
	for precondition.
	(semaphore::release): Add assertion using value returned from
	_M_release.
	* testsuite/30_threads/semaphore/100806.cc: Increase template
	argument for std::counting_semaphore, so constructor
	precondition is met.
	* testsuite/30_threads/semaphore/cons.cc: New test.
	* testsuite/30_threads/semaphore/try_acquire_posix.cc: Remove.
	* testsuite/30_threads/semaphore/platform_try_acquire_for.cc:
	Removed.