codegen.c: order instructions in natural order for loops.

`while` and `until` generates in `cond` `jmpif` `body` `jmp` order.
It used to be in `jmp` `body` `cond` `jmpif` order.

mrbgems/mruby-compiler/core/codegen.c

@@ -1938,14 +1938,13 @@ codegen(codegen_scope *s, node *tree, int val)
 
       if (!val) lp->acc = -1;
       lp->pc0 = new_label(s);
-      pos = genjmp_0(s, OP_JMP);
+      codegen(s, tree->car, VAL);
+      pop();
+      pos = genjmp2_0(s, OP_JMPNOT, cursp(), NOVAL);
       lp->pc1 = new_label(s);
       codegen(s, tree->cdr, NOVAL);
+      genjmp(s, OP_JMP, lp->pc0);
       dispatch(s, pos);
-      codegen(s, tree->car, VAL);
-      pop();
-      genjmp2(s, OP_JMPIF, cursp(), lp->pc1, NOVAL);
-
       loop_pop(s, val);
     }
     break;
@@ -1957,14 +1956,13 @@ codegen(codegen_scope *s, node *tree, int val)
 
       if (!val) lp->acc = -1;
       lp->pc0 = new_label(s);
-      pos = genjmp_0(s, OP_JMP);
+      codegen(s, tree->car, VAL);
+      pop();
+      pos = genjmp2_0(s, OP_JMPIF, cursp(), NOVAL);
       lp->pc1 = new_label(s);
       codegen(s, tree->cdr, NOVAL);
+      genjmp(s, OP_JMP, lp->pc0);
       dispatch(s, pos);
-      codegen(s, tree->car, VAL);
-      pop();
-      genjmp2(s, OP_JMPNOT, cursp(), lp->pc1, NOVAL);
-
       loop_pop(s, val);
     }
     break;