Besides just generating and consuming the lists, this includes:
- Calling nm with the right options in extract_symbols.py. Such as not demangling C++ names, which AIX nm does by default, and accepting both 32/64-bit names.
- Not having nm sort the list of symbols or we may run in to memory issues on debug builds, as nm calls a 32-bit sort.
- Defaulting to having LLVM_EXPORT_SYMBOLS_FOR_PLUGINS on for AIX
- CMake versions prior to 3.16 set the -brtl linker flag globally on AIX. Clear it out early on so we don't run into failures. We will set it as needed.