make sure that nsproxy_cache is initialized early enough

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 50d20ab..cc37a55 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -68,6 +68,7 @@
 void free_nsproxy(struct nsproxy *ns);
 int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
 	struct fs_struct *);
+int __init nsproxy_cache_init(void);
 
 static inline void put_nsproxy(struct nsproxy *ns)
 {