For some platforms (Arch Linux, at least), `git status` reports errors on stdout instead of stderr, so we need to redirect that to `/dev/null` too. This also prevents `git status` from logging output when the yosys directory is a git repo, but is missing the abc folder.
Partially reverts commit 9c5bffcf93.
The reasoning behind this is that setup.py is intended to strictly consume the Makefile and not be consumed by it. The attempt at using them recursively has caused a number of issues and has rendered Pyosys unusable to some users: See https://github.com/YosysHQ/yosys/issues/5012
Additionally, unlike the previous pyosys installation target, the wheel installation does not respect PREFIX=, only venvs.
For installation inside a venv, the intended method should remain a user manually executing `pip3 install .` instead of relying on the Makefile.
Essentially, something is attempting to build the Yosys EXE when you build libyosys.so now. With `ENABLE_PYTHON_CONFIG_EMBED=0`, the Yosys EXE will always fail to build.
Furthermore, because `ENABLE_PYOSYS` now attempts to build a wheel, building a wheel has become recursive.
This commit uses a supplementary set of libs for the EXE (EXE_LIBS) so it and libyosys.so can be built simultaneously, as well as a new Makefile flag, `ENABLE_WHEEL`, to prevent the aforementioned recursion.
I also enabled aarch64 Linux in the CI because it's publicly available now.
As in #4986, `check-git-abc` is misleading if Yosys itself isn't a git repository.
So check `git status` before suggesting `git` based solutions, providing alternative suggestions for using ABCEXTERNAL (which bypasses `check-git-abc`), or downloading release tar (noting that the 'Source code' archives won't work, which is probably how they ended up in this situtation).
Make will happily consider a target available if it's zero sized.
When writing output files with shell redirections for commands that usually
succeed we can apply the `|| rm $@` pattern.
For commands where --help exits with failure we always rerun the recipe
instead.
