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/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c71e91b..23df7771 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1520,7 +1520,7 @@
 	return 0;
 }
 
-static struct seq_operations show_ftrace_seq_ops = {
+static const struct seq_operations show_ftrace_seq_ops = {
 	.start = t_start,
 	.next = t_next,
 	.stop = t_stop,
@@ -2459,7 +2459,7 @@
 	return 0;
 }
 
-static struct seq_operations ftrace_graph_seq_ops = {
+static const struct seq_operations ftrace_graph_seq_ops = {
 	.start = g_start,
 	.next = g_next,
 	.stop = g_stop,