Use `uint16_t` for `argc` and `acc` of `mrb_callinfo`
This is because it is enough to express the range up to (-1..255) or (-3..255).
@@ -155,8 +155,8 @@ typedef struct {
struct REnv *env;
const mrb_code *pc; /* return address */
const mrb_code *err; /* error position */
- mrb_int argc;
- mrb_int acc;
+ int16_t argc;
+ int16_t acc;
struct RClass *target_class;
} mrb_callinfo;
