wheels: fix builds, add linux aarch64 to ci

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.

setup.py

@@ -40,8 +40,8 @@ class libyosys_so_ext(Extension):
         )
         self.args = [
             "ENABLE_PYOSYS=1",
-            # Wheel meant to be imported from interpreter
-            "ENABLE_PYTHON_CONFIG_EMBED=0",
+            # Prevent recursive wheel build
+            "ENABLE_WHEEL=0",
             # Would need to be installed separately by the user
             "ENABLE_TCL=0",
             "ENABLE_READLINE=0",