PR libstdc++/88881 fix filesystem::symlink_status for Windows

PR libstdc++/88881 fix filesystem::symlink_status for Windows

The fix for PR 88881 only added a workaround to filesystem::status, but
filesystem::symlink_status is also affected by the _wstat bug and needs
the same workaround.

The recent change to optimize path::parent_path() means that the
workaround can be simplified to just use parent_path().

	PR libstdc++/88881
	* src/c++17/fs_ops.cc [_GLIBCXX_FILESYSTEM_IS_WINDOWS]
	(status(const path&, error_code&)): Use parent_path() to remove
	trailing slash.
	(symlink_status(const path&, error_code&)): Duplicate workaround for
	bug in _wstat for paths with trailing slash.
	* testsuite/27_io/filesystem/operations/remove_all.cc: Check path
	with trailing slash.
	* testsuite/27_io/filesystem/operations/status.cc: Likewise.
	* testsuite/27_io/filesystem/operations/symlink_status.cc: Likewise.

From-SVN: r271755