Fix our handling of literals and types in LLVM (#7575).
This bug was introduced in the recent fix for #7571, that extended some existing infastructure in the LLVM backend that handled the conflict between LLVM's return type from comparison operations (i1) and what GHC expects (word). By extending it to handle literals though, we forced all literals to be i1 or word, breaking other code. This patch resolves this breakage and handles #7571 still, cleaning up the code for both a little. The overall approach is not ideal but changing that is left for the future.