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

[Corentin Jabot 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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cor3ntin wrote:

I'm not opposed to having it there if we do not find a better place (I think having it in Lexer might be a tad annoying)

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