[Modules] Do not inherit DirectCC1Mode in subInstance

Stop inheriting DirectCC1 clang option in subInstance for module
loading. The option was inherited when it was used for both direct cc1
scanning (generating direct cc1 compile commands) and compilation
(consume direct cc1 commands), but it is not really useful for
compilation since the explicit module builds that use the configuration
do not spawn sub-instance for module loading.

Except LLDB, which does a slight different variant of the explicit
module that do not have swift-driver cooridination and replies on the
subInstance to load swiftmodule. When such configuration is used, if
DirectCC1 compile option is inherited without any extra cc1 arguments,
the clang importer inside the sub-instance is actually malformed,
causing the swift instance failed to be created. Stop inheriting the
DirectCC1 compilation option will allow sub-instance to be created.

rdar://135611011

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1782,8 +1782,6 @@ void InterfaceSubContextDelegateImpl::inheritOptionsForBuildingInterface(
         Feature::LayoutPrespecialization);
   }
 
-  genericSubInvocation.getClangImporterOptions().DirectClangCC1ModuleBuild =
-      clangImporterOpts.DirectClangCC1ModuleBuild;
   genericSubInvocation.getClangImporterOptions().ClangImporterDirectCC1Scan =
       clangImporterOpts.ClangImporterDirectCC1Scan;