Standard way to supply hints to branches

[Walter Bright]

```
int fun(int x)
{
      int y;
      if (x < 0)
          goto Lreturn0;

      y = x * x;

      return y;
Lreturn0:
      return 0;
}
```

or:
```
int fun(int x)
{
      if (x < 0)
          goto Lreturn0;

     {
      int y = x * x;

      return y;
     }
Lreturn0:
      return 0;
}
```