This will eventually be used to enable running with Tree Builder v2.
For now, when it is disabled it puts CodeGen v2 into compatibility mode,
disabling features which weren't present in CodeGen v1 so that its
output can be understood by Tree Builder v1.
These aren't used for anything yet, but should be useful for stable IDs
when printing nodes before and after passes and for faster cycle
detection than the current map of pointers.
- Change member and parent offsets to work in bits, not bytes
- Printer still displays offsets in bytes, with decimals when using
bitfields
- AddPadding: Don't pad bitfields
- CodeGen: Emit code for bitfields
