4e67e08efd
This switches from a custom list of architectures to use the target-lexicon crate. - "set is_64bit=1; isa x86" is replaced with "target x86_64", and similar for other architectures, and the `is_64bit` flag is removed entirely. - The `is_compressed` flag is removed too; it's no longer being used to control REX prefixes on x86-64, ARM and Thumb are separate architectures in target-lexicon, and we can figure out how to select RISC-V compressed encodings when we're ready.