constify do_coredump() argument

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/coredump.c b/fs/coredump.c
index dc1f937..62406b6 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -485,7 +485,7 @@
 	return err;
 }
 
-void do_coredump(siginfo_t *siginfo)
+void do_coredump(const siginfo_t *siginfo)
 {
 	struct core_state core_state;
 	struct core_name cn;