[llvm] [CMake] Followup to #102396 and restore old DynamicLibrary symbols behavior (PR #102671)

[Jake Egan via llvm-commits]

jakeegan wrote:

It did fix the ppc64 bot https://lab.llvm.org/buildbot/#/builders/64/builds/668. Would it make sense to guard this PR for AIX only, as a temporary fix, then we'll investigate the difference further?

https://github.com/llvm/llvm-project/pull/102671