* `misc/__init__.py`:
* checks if there's a `yosys-abc` in the same directory - if yes, sets the variable `sys._pyosys_abc`
* checks if there's a `share` in the same directory - if yes, sets the variable `sys._pyosys_share_dirname`
* `yosys.cc::init_share_dirname`: check for `sys._pyosys_share_dirname`, use it at the highest priority if Python is enabled
* `yosys.cc::init_abc_executable_name`: check for `sys._pyosys_abc`, use it at at the highest priority if Python is enabled
* `Makefile`: add new target, `share`, to only create the extra targets
* `setup.py`: compile libyosys.so, yosys-abc and share, and copy them all as part of the pyosys build
* `test/arch/ecp5/add_sub.py`: ported `add_sub.ys` to Python to act as a test for the share directory and abc with Python wheels, used in CI