[llvm] [llvm-gsymutil] Address merged-funcs test non-determinism (PR #122308)

[Vladimir Vereschaka via llvm-commits]

vvereschaka wrote:

Hi @alx32 ,
any progress with failed `macho-merged-funcs-dwarf.yaml` test on the expensive builders?

https://lab.llvm.org/buildbot/#/builders/187/builds/3737

https://github.com/llvm/llvm-project/pull/122308