Tweak the slice interners.

All the slice interners have a wrapper that handles the empty slice
case. We can instead handle this in the `slice_interners!` macro,
avoiding the need for most of the wrappers, and allowing the interner
functions to be renamed from `_intern_foos` to `intern_foos`.

The two exceptions:
- intern_predicates: I kept this wrapper because there's a FIXME
  comment about a possible future change.
- intern_poly_existential_predicates: I kept this wrapper because it
  asserts that the slice is empty and sorted.

0 files changed, 0 insertions, 0 deletions