[Bug tree-optimization/114894] `a == 0 ? 0 : a * b` -> `a * b` likewise for `a & b`

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114894

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note we should catch this too:
```
int fmul2(unsigned a, int b)
{
        int c = a * b;
        int d = a != 0;
        return c & -d;
}

```

Which is more complex ...