We need to update this code before introducing an 'fneg' instruction in IR, so we might as well kill off the integer neg/not queries too.
This is no-functional-change-intended for integer code and most vector code. For vectors, we can see that the 'match' API allows for undef elements in constants, so we optimize those cases better.
Ideally, there would be a test for each code diff, but I don't see evidence of that for the existing code, so I didn't try very hard to come up with new vector tests for each code change.