Added stack depth tracking to handle jumping out of blocks nested inside

expressions. This is not only a fix due to the labeled breaks, e.g. the
following program have always bugged until now:

int main()
{
  foreach (({1,2,3}), int j)
    do
      if (17 + j + gauge {break;}) return 0;
    while (0);
}

Rev: src/docode.c:1.97