[Bug tree-optimization/118804] redundant if (x == CST && y == CST) not removed

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118804

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(e)VRP can handle the non-constant case already too:
```
bool bar (int x, int y, int z) {
    if (x == y)
      return true;
    if (x == z)
      if (y == z)
        return true;
    return f(x,y);
}
```

Though not like:
```
bool bar (int x, int y, int z) {
    if (x == y)
      return true;
    if (x == z && y == z)
        return true;
    return f(x,y);
}
```