[llvm] [LTO] Introduce helper functions to add GUIDs to ImportList (NFC) (PR #105555)

[Jan Voung via llvm-commits]

================
@@ -887,8 +902,8 @@ static void computeImportForFunction(
           // If insert doesn't happen, there must be an existing entry keyed by
----------------
jvoung wrote:

nit: could consider shortening the comment. It might be that only the "Note `ExportLists` only keeps track of exports due to imported definitions." is useful now?

https://github.com/llvm/llvm-project/pull/105555