Add test for Apple's `-weak_framework` linker argument The [`-weak_framework`](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html) linker argument can sometimes be useful to reduce startup times, and to link newer frameworks while still having older deployment targets. So I made a test to ensure that it continues to work. Discussed in https://github.com/rust-lang/rust/issues/99427.