This enables configuration of build parallelism with the Ninja generator by
passing arguments on the command line to CMake. For example,

  cmake \
    '-DCMAKE_JOB_POOLS:STRING=compile=5;link=2' \
    -DCMAKE_JOB_POOL_COMPILE:STRING=compile \
    -DCMAKE_JOB_POOL_LINK:STRING=link \
      ~/src/MyProject