seq_file: constify seq_operations

Make all seq_operations structs const, to help mitigate against
revectoring user-triggerable function pointers.

This is derived from the grsecurity patch, although generated from scratch
because it's simpler than extracting the changes from there.

Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 1ee27cc..07fa612 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -91,7 +91,7 @@
 }
 
 
-static struct seq_operations misc_seq_ops = {
+static const struct seq_operations misc_seq_ops = {
 	.start = misc_seq_start,
 	.next  = misc_seq_next,
 	.stop  = misc_seq_stop,