Introspection: support Mach-O fixup chains

[Tpt]

Apple introduced a new feature in Mach-O binaries called fixup chains. Our current introspection code does not support it. By default cargo does not make use of it for any macOS target so it's likely not a big priority but it would be great to support them anyway.

See #5034 that adds a clear error message when fixup chains are used.