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

[Sergei Barannikov via cfe-commits]

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@@ -2090,6 +2203,10 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks){
 
   SourceLocation UDSuffixTokLoc;
 
+  llvm::TextEncodingConverter *Converter = nullptr;
+  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && TEC)
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s-barannikov wrote:

```suggestion
  if (isOrdinary() && TEC)
```

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