Place optable in ROM
@@ -1022,7 +1022,7 @@ mrb_vm_exec(mrb_state *mrb, const struct RProc *proc, const mrb_code *pc)
const struct mrb_irep_catch_handler *ch;
#ifdef DIRECT_THREADED
- static void *optable[] = {
+ static const void * const optable[] = {
#define OPCODE(x,_) &&L_OP_ ## x,
#include "mruby/ops.h"
#undef OPCODE
