get rid of s_files and files_lock

The only thing we need it for is alt-sysrq-r (emergency remount r/o)
and these days we can do just as well without going through the
list of files.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
int finish_no_open(struct file *file, struct dentry *dentry)
{
	file->f_path.dentry = dentry;
	return 1;
}

int finish_no_open(struct file *file, struct dentry *dentry)
{
	file->f_path.dentry = dentry;
	return 1;
}
