Revert "[lldb] Enable C++14 when evaluating expressions in a C++14 frame"

This reverts commit 5f88f39. It broke these
three tests on the Window bot:
  lldb-api :: commands/expression/completion/TestExprCompletion.py
  lldb-api :: lang/cpp/scope/TestCppScope.py
  lldb-api :: lang/cpp/standards/cpp11/TestCPP11Standard.py

Author: Teemperor

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -491,11 +491,9 @@ ClangExpressionParser::ClangExpressionParser(
     // be re-evaluated in the future.
     lang_opts.CPlusPlus11 = true;
     break;
-  case lldb::eLanguageTypeC_plus_plus_14:
-    lang_opts.CPlusPlus14 = true;
-    LLVM_FALLTHROUGH;
   case lldb::eLanguageTypeC_plus_plus:
   case lldb::eLanguageTypeC_plus_plus_11:
+  case lldb::eLanguageTypeC_plus_plus_14:
     lang_opts.CPlusPlus11 = true;
     m_compiler->getHeaderSearchOpts().UseLibcxx = true;
     LLVM_FALLTHROUGH;