Add `const` specifier to `cipush()`; ref
@@ -264,7 +264,7 @@ top_proc(mrb_state *mrb, const struct RProc *proc)
static inline mrb_callinfo*
cipush(mrb_state *mrb, const mrb_code *pc, int push_stacks, int acc,
- struct RClass *target_class, struct RProc *proc, mrb_sym mid, int argc)
+ struct RClass *target_class, const struct RProc *proc, mrb_sym mid, int argc)
{
struct mrb_context *c = mrb->c;
mrb_callinfo *ci = c->ci;
