Merge pull request #6949 from slavapestov/remove-variadic-generics-feature-5.9

[lldb] Update for removal of swift::Feature::VariadicGenerics [5.9]

Author: hborla

lldb/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp

@@ -1342,7 +1342,6 @@ static llvm::Expected<ParsedExpression> ParseAndImport(
       sc.target_sp->GetSwiftEnableBareSlashRegex();
   invocation.getLangOptions().EnableBareSlashRegexLiterals =
       enable_bare_slash_regex_literals;
-  invocation.getLangOptions().Features.insert(swift::Feature::VariadicGenerics);
 
   auto should_use_prestable_abi = [&]() {
     lldb::StackFrameSP this_frame_sp(stack_frame_wp.lock());