- NOMINMAX to fix confusion between std::max(..) and max(..) macro redefinition
- BOOST_USE_WINDOWS_H to prevent boost from redefining win32 APIs
- WIN32_LEAN_AND_MEAN to fix include ordering issues with winsock.h
So that we can use it from a piece of flow code without breaking module
boundaries.
Also rename generated-constants to crc32c-generated-constants so that
it's more apparent that they're related files.