Fixed bogus comparison functions

Fixed bogus comparison functions

Found by michaelforney on Github.

- On neq0     , I used ^ instead of |
- On zerocmp32, I used + instead of |

Both errors lead to false negatives: you *think* all went well and the
number looks like it is indeed, zero, but it's not.  This could lead
to vulnerabilities in practice, where we could use the flaws in the
comparison functions to find pseudo-collisions, that defeat the checks
without being actual collisions.

Oops.