PR libstdc++/66011

	PR libstdc++/66011
	* acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Check for fchmod and
	sendfile.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* src/filesystem/ops.cc (do_copy_file): Fix arguments to open(). Do
	not return after copying contents. Use fchmod, fchmodat, and sendfile
	when available.
	(current_path, permissions, space): Use errno not return value.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@223196 138bc75d-0d04-0410-961f-82ee72b054a4