fixup! codegen.c: resurrect `s->lastpc` to reduce `iseq` scans.
@@ -462,13 +462,7 @@ mrb_prev_pc(codegen_scope *s, const mrb_code *pc)
#define pc_addr(s) &((s)->iseq[(s)->pc])
#define addr_pc(s, addr) (uint32_t)((addr) - s->iseq)
-
-static void
-rewind_pc(codegen_scope *s)
-{
- /* should not be called when s->pc is 0 (top) */
- s->pc = addr_pc(s, mrb_prev_pc(s, pc_addr(s)));
-}
+#define rewind_pc(s) s->pc = s->lastpc
static struct mrb_insn_data
mrb_last_insn(codegen_scope *s)
