[llvm-branch-commits] [llvm] [LTT] Add `unknown` branch weights when lowering type tests with conditional (PR #170752)

[Peter Collingbourne via llvm-branch-commits]

pcc wrote:

What does this function do? The frontend is expected to add unlikely annotations and we don't want this function to override them.

https://github.com/llvm/llvm-project/pull/170752