More of c++20 ready to be used.

Complete C++20 Modules Support with GCC

by Boris Kolpackov

From the article:

build2 now provides conforming and scalable support for all the major C++20 Modules features when used with GCC. This includes named modules, module partitions (both interface and implementation), header unit importation, and include translation. All of these features are also supported in libraries, including consumption of installed libraries with information about modules and importable headers conveyed in pkg-config files. As part of this effort we have also created a collection of examples that demonstrate C++20 Modules features that impact the build process...