MachO LLD - Crash when both ObjC category merge + relative method lists are enabled

[alx32]

A crash happens when both ObjC category merge + relative method lists are enabled.

Repro can be tested by adding -objc_relative_method_lists to lld invocations in lld/test/MachO/objc-category-merging-minimal.s

[alx32]

Fixed by PR #104081

[llvmbot]

@llvm/issue-subscribers-lld-macho

Author: None (alx32)

A crash happens when both ObjC category merge + relative method lists are enabled.

Repro can be tested by adding -objc_relative_method_lists to lld invocations in lld/test/MachO/objc-category-merging-minimal.s

[alx32]

/cherry-pick 0df9189

To not have this scenario crash in the 19.0 branch