[llvm] [LTO] Fix a crash with thin LTO caching and asm output (PR #138203)

[Teresa Johnson via llvm-commits]

teresajohnson wrote:

Is this fall out of https://github.com/llvm/llvm-project/pull/136121? If so, I wonder if that PR should be reverted instead - it turns out that went in without a full review / approval, and if it is causing subtle bugs I would prefer to revert that one.

https://github.com/llvm/llvm-project/pull/138203