Fix the first operand of `struct mrb_insn_data` to 32 bits
Because there is `W` type, at least 24 bits must be represented.
@@ -114,7 +114,7 @@ MRB_API mrb_value mrb_load_irep_buf_cxt(mrb_state*, const void*, size_t, mrbc_co
struct mrb_insn_data {
uint8_t insn;
- uint16_t a;
+ uint32_t a;
uint16_t b;
uint16_t c;
const mrb_code *addr;
