switch to kitware's ninja as the default upstream for ninja and configure it to respect jobserver in spack env depfile -o Makefile

[robertu94]

Summary

Right now if you use spack env depfile -o Makefile; make -j $(nproc) you get more build threads than $(nproc) because ninja doesn't understand posix jobservers and spawns more threads than it should. The Kitware fork of ninja has the necessary patches to make this work.

Rationale

The Ninja authors are extremely resistant to adding new features, and larger features languish for years without being merged, and kitware in addition to being responsible maintainers of cmake maintains a fork of ninja that is widely adopted by the broader community (it's what you get when you pip install ninja).

Description

The only alternatives are 1) to ignore this and suffer ninja not respecting the jobsever. or 2) maintain the patches ourselves (more work), 3) somehow get the Ninja authors to merge ninja-build/ninja#1139

Additional information

No response

General information

• I have searched the issues of this repo and believe this is not a duplicate