Fix redo keyword

Add `OP_NOP` to distinguish `retry` and jump targets while maintaining instruction compatibility.
Ideally, it might be preferable to separate them into `OP_REDO`.

fixed #6439

mrbgems/mruby-compiler/core/codegen.c

@@ -1323,6 +1323,7 @@ for_body(codegen_scope *s, node *tree)
   /* construct loop */
   lp = loop_push(s, LOOP_FOR);
   lp->pc1 = new_label(s);
+  genop_0(s, OP_NOP); /* for redo */
 
   /* loop body */
   codegen(s, tree->cdr->cdr->car, VAL);
@@ -2589,6 +2590,7 @@ codegen(codegen_scope *s, node *tree, int val)
         pos = genjmp2_0(s, OP_JMPIF, cursp(), NOVAL);
       }
       lp->pc1 = new_label(s);
+      genop_0(s, OP_NOP); /* for redo */
       codegen(s, tree->cdr, NOVAL);
       genjmp(s, OP_JMP, lp->pc0);
       dispatch(s, pos);