sysctl: Stop implicitly passing current into sysctl_table_root.lookup

Passing nsproxy into sysctl_table_root.lookup was a premature
optimization in attempt to avoid depending on current.  The
directory /proc/self/sys has not appeared and if and when
it does this code will need to be reviewed closely and reworked
anyway.  So remove the premature optimization.

Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 697e160..f166ca0 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -155,8 +155,7 @@
 
 struct ctl_table_root {
 	struct ctl_table_set default_set;
-	struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
-					   struct nsproxy *namespaces);
+	struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 };