Don't use xclose() in splice_fd_to_stdinout()

The splice fd might have been closed, and a double-close here shouldn't
be a concern because we're not doing any interesting multithreaded
things and it's local to this function.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

c_src/cmd_fsck.c

@@ -86,7 +86,7 @@ static int splice_fd_to_stdinout(int fd)
 			stdin_closed = true;
 	}
 
-	xclose(fd);
+	close(fd);
 	return 0;
 }