[clang] [clang-tools-extra] [clang][lex] Always pass suggested module to `InclusionDirective()` callback (PR #81061)

[Ben Langmuir via cfe-commits]

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@@ -2265,7 +2265,6 @@ Preprocessor::ImportAction Preprocessor::HandleHeaderIncludeOrImport(
       UsableHeaderUnit = true;
     else if (!IsImportDecl) {
       // This is a Header Unit that we do not include-translate
-      SuggestedModule = ModuleMap::KnownHeader();
       SM = nullptr;
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benlangmuir wrote:

Maybe we should rename `SM` to reflect the difference in behaviour?

https://github.com/llvm/llvm-project/pull/81061