<sys/stat.h>, <sys/types.h>, <unistd.h>, (STDOUT_FILENO):

<sys/stat.h>, <sys/types.h>, <unistd.h>, (STDOUT_FILENO):
Remove; no longer needed.
"quotearg.h": Add include.
(file_name): Do not bother to explicitly initialize to NULL; it's less
efficient on some hosts.
(close_stdout_status): Remove test as to whether stdout was already
closed; it breaks for the case "echo x | sort >&-".
Quote file name colons.
Do not assume that _("write error") lacks format strings.