Use a backend from Samurai, a Ninja-Build re-implementation

[SamuraiCrow]

https://github.com/araspik/samurai uses C99 instead of C++ runtimes to reimplement Ninja-build independently of the original source base. It should be compilable with https://github.com/LibCodeGen/sqbe-c so that the builds can be modular in the same way as objects and module generators could be modularized.

[SamuraiCrow]

https://github.com/LibBuildGen has been created and now contains a fork of Samurai to allow the modular reuse as a Ninja-build library offshoot. Making build/make frontends can be done using it someday.