[llvm] [MemProf] Fix when CallStackTrie is a single chain with multi alloc type (PR #79433)

[via llvm-commits]

lifengxiang1025 wrote:

I met one coredump when I try memprof in our benchmark. After debugging, I found there exists three same callstack but with different alloc type when build one AllocTrie. I don't know why there are same callstack. So I can't write test case now.

https://github.com/llvm/llvm-project/pull/79433