From https://github.com/llvm/llvm-project/pull/169225#issuecomment-4024377289: There was a dependency cycle involving the C++ language runtime: ``` //lldb/source/Plugins/TypeSystem/Clang:Clang -> //lldb/source/Plugins/ExpressionParser/Clang:Clang -> //lldb/source/Plugins/LanguageRuntime/CPlusPlus:CPlusPlus -> //lldb/source/Plugins/TypeSystem/Clang:Clang ``` `ExpressionParserClang` doesn't need to depend on the C++ language runtime. It only included a file, but didn't use it. This PR removes that dependency.