switch mount_capable() to fs_context

	now both callers of mount_capable() have access to fs_context;
the only difference is that for sget_fc() we have the possibility
of fc->global being true, while for legacy_get_tree() it's guaranteed
to be impossible.  Unify to more generic variant...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/internal.h b/fs/internal.h
index 65db901..b089a48 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -114,7 +114,7 @@ extern struct file *alloc_empty_file_noaccount(int, const struct cred *);
 extern int reconfigure_super(struct fs_context *);
 extern bool trylock_super(struct super_block *sb);
 extern struct super_block *user_get_super(dev_t);
-extern bool mount_capable(struct file_system_type *, struct user_namespace *);
+extern bool mount_capable(struct fs_context *);
 
 /*
  * open.c