macOS linker warnings in macOS ventura

Turns out ld shipped with Xcode 14+ emits a warning when using -undefined dynamic_lookup.`

ld: warning: -undefined dynamic_lookup may not work with chained fixups

Some investigation reveals that in fact -undefined dynamic_lookup doesn't work when:

• Link a shared library with the option
• Link it with a program that uses the chained-fixup introduced from macOS 12 and iOS 15

This is because -undefined dynamic_lookup uses lazy-bindings and they won't be bound while dyld fixes-up by traversing chained-fixup info.

However, we build extension modules with as bundles (-bundle) and they are loaded only through
dlopen, so it's safe to use -undefined dynamic_lookup in theory. So the warning produced by ld64 is
likely to be a false-positive.

ld64 also provides the -bundle_loader <executable> option, which allows resolving symbols defined in the executable symbol table while linking. It behaves almost the same with -undefined dynamic_lookup, but it makes the following changes:

• Require that unresolved symbols among input objects must be defined in the executable.
• Lazy symbol binding will lookup only the symbol table of the bundle loader executable. (-undefined dynamic_lookup lookups all symbol tables as flat namespace)

See "New Features" subsection under "Linking" section for chained fixup
developer.apple.com/documentation/xcode-release-notes/xcode-13-release-notes for more information.

Also, check the same problem in ruby where most of this information is taken from.

No files, tests, or entry points are named. Start by locating CPython's macOS extension-module linker configuration and the uses of -undefined dynamic_lookup; compare the current behavior with ld64's -bundle_loader option. Done means the Ventura/Xcode 14+ warning is addressed without breaking extension-module loading.