constify copy_siginfo_to_user{,32}()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/signal.c b/kernel/signal.c
index ded28b9..940b30e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2723,7 +2723,7 @@
 
 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
 
-int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
+int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
 {
 	int err;