[clang] [llvm] Enable fexec-charset option (PR #138895)

[Sergei Barannikov via cfe-commits]

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@@ -198,6 +223,7 @@ class Preprocessor {
   std::unique_ptr<ScratchBuffer> ScratchBuf;
   HeaderSearch      &HeaderInfo;
   ModuleLoader      &TheModuleLoader;
+  TextEncodingConfig TEC;
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s-barannikov wrote:

Why is it a member of Preprocessor? -fexec-charset shouldn't affect the preprocessor behavior (?)

https://github.com/llvm/llvm-project/pull/138895