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.

From-SVN: r223196