[llvm] [Bolt] fix a wrong relocation update issue with weak references (PR #69136)

[via llvm-commits]

linsinan1995 wrote:

Hi @yota9 , sorry for a late reply.

I made several changes,
- change assembly code to obj2yaml output, since I notice the linker could impact the result.
- add both func_1 and  func_2 tests for weak undefined and normal cases.

I still use isWeakReference, since weak reference is a term for such a case. Is it ok?

https://github.com/llvm/llvm-project/pull/69136