unix: add aarch64-apple-darwin builds for CPython 3.8

This should address #118.

I haven't tested these builds thoroughly and I'm a bit surprised the build
seemed to _just work_. Surely there must be something wrong lingering under
the surface...

Author: indygreg

.github/workflows/apple.yml

@@ -118,8 +118,17 @@ jobs:
       matrix:
         build:
           # macOS on Apple hardware. Can't do PGO because GitHub Apple hardware
-          # is Intel. Can't do Python 3.8 because we don't support cross-compiling
-          # until 3.9.
+          # is Intel.
+          - target_triple: 'aarch64-apple-darwin'
+            py: 'cpython-3.8'
+            optimizations: 'debug'
+          - target_triple: 'aarch64-apple-darwin'
+            py: 'cpython-3.8'
+            optimizations: 'noopt'
+          - target_triple: 'aarch64-apple-darwin'
+            py: 'cpython-3.8'
+            optimizations: 'lto'
+
           - target_triple: 'aarch64-apple-darwin'
             py: 'cpython-3.9'
             optimizations: 'debug'

cpython-unix/disabled-static-modules.3.8.aarch64-apple-darwin

@@ -0,0 +1,20 @@
+# We don't support GDBM because it is GPL v3.
+_gdbm
+# Not available on macOS.
+nis
+# Not available on macOS.
+ossaudiodev
+# Not available on macOS.
+spwd
+
+# Ideally this would only be disabled while cross-compiling. We can't build it
+# as a built-in extension via static-modules. And when letting setup.py build
+# it, it builds for the host architecture during cross-builds, which upsets
+# our validation script when it screens for the target machine type of
+# binaries. So just disable it.
+_testcapi
+
+# Similar story as _testcapi. The extension exists to test the limited API,
+# which we don't really care about. Statically building it runs into problems
+# and cross-compiling emits wrong machine type when built via setup.py.
+xxlimited

cpython-unix/targets.yml

@@ -56,6 +56,7 @@ aarch64-apple-darwin:
   host_platforms:
     - macos
   pythons_supported:
+    - '3.8'
     - '3.9'
     - '3.10'
   needs_toolchain: true

src/release.rs

@@ -33,7 +33,7 @@ pub static RELEASE_TRIPLES: Lazy<BTreeMap<&'static str, TripleRelease>> = Lazy::
         TripleRelease {
             suffixes: macos_suffixes.clone(),
             install_only_suffix: "pgo+lto",
-            python_version_requirement: Some(VersionReq::parse(">=3.9").unwrap()),
+            python_version_requirement: None,
         },
     );
     h.insert(