Bug in SSA Translation

Test program:

```
func bug(N: Int)
{
    var p=2
    while( p < N ) {
        if (p) {
            p = p + 1
        }
    }
    while ( p < N ) {
        p = p + 1
    }
}
```

Details of the bug are at [https://github.com/CompilerProgramming/ez-lang/wiki/Debugging-Optimizing-Compiler](https://github.com/CompilerProgramming/ez-lang/wiki/Debugging-Optimizing-Compiler)