[llvm] [LTO] Turn ImportMapTy into a proper class (NFC) (PR #105748)

[Kazu Hirata via llvm-commits]

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@@ -102,7 +102,39 @@ class FunctionImporter {
   /// elsewhere, typically by the in-memory ModuleSummaryIndex the importing
   /// decisions are made from (the module path for each summary is owned by the
   /// index's module path string table).
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kazutakahirata wrote:

Done.

https://github.com/llvm/llvm-project/pull/105748