ld64 shipped with Xcode 14 emits a warning when using `-undefined dynamic_lookup`. ``` ld: warning: -undefined dynamic_lookup may not work with chained fixups ``` Actually, `-undefined dynamic_lookup` doesn't work when: 1. Link a *shared library* with the option 2. Link it with a program that uses the chained-fixup introduced from macOS 12 and iOS 15 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 exts as *bundles* 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 false-positive, and it results failure of option checking in configuration. Therefore, it would be an option to ignore the warning during our configuration. On the other hand, `-undefined dynamic_lookup` is already deprecated on all darwin platforms except for macOS, so it's good time to get rid of the option. ld64 also provides `-bundle_loader <executable>` option, which allows to resolve symbols defined in the executable symtab while linking. It behaves almost the same with `-undefined dynamic_lookup`, but it makes the following changes: 1. Require that unresolved symbols among input objects must be defined in the executable. 2. Lazy symbol binding will lookup only the symtab of the bundle loader executable. (`-undefined dynamic_lookup` lookups all symtab as flat namespace) This adds `-bundle_loader $(RUBY)` when non-EXTSTATIC configuration by assuming ruby executable can be linked before building exts. See "New Features" subsection under "Linking" section for chained fixup https://developer.apple.com/documentation/xcode-release-notes/xcode-13-release-notes