Forgot to rename operator to risch-operator in one place
Tests didn't catch this case. Really need to add a test for it. We
need to find a test that exercises `intsetup` so that it returns T for
`risch-operator`. (`intsetup` is full of gotos that it's hard to
figure out path that will lead to that return. At first glance,
anyway.)
Rename `operator` to `risch-operator` in `rischint` and `rischform`
and return `risch-operator` as another return value. Update
`rischint` to handle the extra return value.
`intsetup` also used to set `operator` to T in one place before
returning. Instead just return T as the second value in that one
place and return NIL in the only other return.
When we renamed `beta` to `risch-beta`, we forgot to define
`risch-beta` in two functions. Add it the to `prog` to get fix the
compiler warning about `risch-beta` being undefined.
