setup: drop legacy osx compiler tuning to enable universal builds
This was triggering deprecation warnings about migrating to `packaging.version`
from `distutils` Version classes with `make local`. But rather than migrate
that code, let's just get rid of some ~10-12 year old workarounds. As a bonus,
the cext libraries that are built are now universal binaries containing x86_64
and arm64 images (at least when built on macOS 11.4 with Xcode 12.5 and the
universal version of Python 3.9.13).
Several things to note here:
- Apple dropped support for 10.15 in Nov 2022, and OS X Lion that is
referenced is 10.7 (unsupported since late 2014)
- `xcode4` was basically always True because of the `>=` check (10.8 used
Xcode 5, and I have Xcode 10.2 on 10.14)
- `xcode51` was always False for modern-ish Xcode, because of the exact
version string matching
- Python 3.8 only supports OS X 10.9+; the Python 3.9.1+ universal installer
is macOS 11+ only, and Python 3.10 drops the x86_64 installer to deliver
only the universal installer.
All of this is to say, the only thing lost by dropping this code on modern Xcode
is that `os.environ['ARCHFLAGS'] = ''` is no longer set. But we probably
shouldn't be setting that anymore, as shown by the universal libraries now being
generated. I was able to `make local` and `python3 run-tests.py --local` with
python 3.9.9, Xcode 10.2, and macOS 10.14.6, and didn't incur any more than the
usual few test errors, so this should still work on some older versions of
macOS.
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Am t
adding a
$ hg mv a b
$ hg ci -Am t1
$ hg debugrename b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
$ hg mv b a
$ hg ci -Am t2
$ hg debugrename a
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
$ hg debugrename --rev 1 b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3