[llvm] [ORC] Add AutoImportGenerator for COFF dllimport auto-import (PR #203914)

[Lang Hames via llvm-commits]

lhames wrote:

> > LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-darwin` running on `doug-worker-3` while building `llvm` at step 6 "test-build-unified-tree-check-all".
> > Full details are available at: https://lab.llvm.org/buildbot/#/builders/23/builds/21523
> > Here is the relevant piece of the build log for the reference
> 
> @mkovacevic99 the tests you added seem to be failing on MacOS. Can you take a look and revert if you need time to investigate?

I'll fix these now. Thanks for the heads up @dyung!

https://github.com/llvm/llvm-project/pull/203914