v2:
- add a basic test for x86 / 32bit. Turns out Windows never uses PROCESS_INSTRUMENTATION_CALLBACK_INFORMATION structure on 32 bit and expects just the callback pointer to be passed, that's why my initial local tests weren't showing any effect from setting the callback on 32 bit; - fix wow64 thunk so it returns status / prints fixme based on correct size check; - keep FIXME in NtSetInformationProcess around for archs where that is not supported; - add a patch which allows setting the callback using old-style parameter (just the callback pointer) which also works on x64.