bpo-46712: Do not Regen Deep-Frozen Modules before Generating Global Objects (gh-32061)

We have to run "make regen-deepfreeze" before running Tools/scripts/generate-global-objects.py; otherwise we will miss any changes to global objects in deep-frozen modules (which aren't committed in the repo).  However, building $(PYTHON_FOR_FREEZE) fails if one of its source files had a global object (e.g. via _Py_ID(...)) added or removed, without generate-global-objects.py running first.  So "make regen-global-objects" would sometimes fail.

We solve this by running generate-global-objects.py before *and* after "make regen-deepfreeze". To speed things up and cut down on noise, we also avoid updating the global objects files if there are no changes to them.

https://bugs.python.org/issue46712