Handle “Small” ObjC Method Lists

[kabiroberai]

MachO files built to target the latest release OSes (iOS 14/macOS 11/etc) use a new "small" format for ObjC method lists, which contain relative 32-bit offsets to methods instead of absolute addresses. Implementing the relative pointer format could also help with Swift ABI support, since Swift does something similar. For implementation details, check out RelativePointer, method_t, and method_list_t in objc-runtime-new.mm.

[DeVaukz]

This should be simple to implement.