[llvm] [ORC][LibraryResolver] Fix ensureFilterBuilt assertion failure and concurrency issue. (PR #166510)

[Vassil Vassilev via llvm-commits]

https://github.com/vgvassilev approved this pull request.

LGTM! Should we land this together with enabling the tests from https://github.com/llvm/llvm-project/pull/166147

https://github.com/llvm/llvm-project/pull/166510