commit 358ca1ae4fa82b97742c5b1a1822d2d9b114b582
author David Brown <david.brown@linaro.org> Tue Jun 25 10:13:20 2019 -0600
committer David Brown <davidb@davidb.org> Mon Jul 29 11:29:21 2019 -0500
tree d5c623739599a056f4c9f61cdbf4d778c566f9c7
parent 1e1be9b3683c594f955ee1edc1d5d8d9f07fb074

Use Ninja instead of Makefiles for Zephyr

Zephyr builds use 'cmake' which can generate either makefiles, or use
the Ninja build tools.  There are several significant advantages to
using Ninja as the build tool:

  - It is significantly faster.  Ninja reads a directory and stats the
    files in it once.  Make often stats a given directory thousands of
    times, many for files that don't even exist.

  - It has better output.  Ninja collects commands together with their
    error output.  When doing multi-cpu builds, Ninja prints a status
    indicator, and only prints fully verbose commands when that command
    fails.  Instead of having to try an piece together a given command
    with its errors, they will always be together.

  - Make's support of multiple CPUs is a crude hack.  Make forks off
    multiple processes to use multiple CPUs.  These processes don't
    communicate with each other (very much), which causes make to often
    continue after enountering errors.  It is common for a multi-CPU
    make invocation to print hundreds or thousands of additional lines
    after an error message.

Nearly all distros have a version of Ninja available in their package
manager, making this change of low cost.

Signed-off-by: David Brown <david.brown@linaro.org>