[Bug tree-optimization/114999] A few missing optimizations due to `a - b` and `b - a` not being detected as negatives of each other

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114999

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
`~a` and `a + 1` are also negative of each other too:

```
int f(int a, int b)
{
  int t = ~a;
  int t1 = -t;
  return t1 == t;
}

int f1(int a)
{
  return (~a) == (-~a);
}


int f2(int a)
{
  return (a) == (-a);
}



int f3(int a)
{
  a = ~a;
  return (a) == (-a);
}


int f4(int a)
{
  a = ~a;
  return f2(a);
}
```

Right now I have a patch which handles `a == -a` for `(a-b)`/`b-a`.
I need one that matches `~a` with the corresponding `a + 1` too.

Note gimple_bitwise_inverted_equal_p should also be expanded to support `-a`
with `a + -1` too.