As discussed in #6952, relying on `git describe` for defining SOF_MAJOR
and friends is very brittle and unreliable. Switch to a static
versions.json file instead.
Note the full `git describe --tags` output is _still_ present in the
binary, this is useful and left unchanged. It's just not used any more
to guess SOF_MAJOR, SOF_MINOR and SOF_MICRO.
Use JSON because CMake and pretty much every other piece of software has
a JSON parser out of the box.
This aligns with linux/Makefile, Zephyr/VERSIONS and probably many
others. - except we use JSON because we're in 2023 so we don't spend
time having fun re-implementing parsers any more.
Signed-off-by: Marc Herbert <marc.herbert@intel.com>
Marc Herbert