message: Skip images without a serialized Swift AST when collecting header
  search options for the scratch context.
  This is both a performance optimization and as a side effect can avoid
  spurious warning messages.
diff: @@ -1037,6 +1037,16 @@ static bool DeserializeAllCompilerFlags(SwiftASTContext &swift_ast,
  return false;
  }
  +/// Return whether this module contains any serialized Swift ASTs.
  +bool HasSwiftModules(Module &module) {
  + SymbolVendor *sym_vendor = module.GetSymbolVendor();
  + if (!sym_vendor)
  + return false;
  +
  + auto ast_file_datas = sym_vendor->GetASTData(eLanguageTypeSwift);
  + return !ast_file_datas.empty();
  +}
  +
  void SwiftASTContext::RemapClangImporterOptions(
  const PathMappingList &path_map) {
  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_TYPES));
  @@ -1361,6 +1371,11 @@ lldb::TypeSystemSP SwiftASTContext::CreateInstance(lldb::LanguageType language,
  for (size_t mi = 0; mi != num_images; ++mi) {
  ModuleSP module_sp = target.GetImages().GetModuleAtIndex(mi);
  + // Skip images without a serialized Swift AST. This avoids
  + // spurious warning messages.
  + if (!HasSwiftModules(*module_sp))
  + continue;
  +
  SwiftASTContext *module_swift_ast = llvm::dyn_cast_or_null<SwiftASTContext>(
  module_sp->GetTypeSystemForLanguage(lldb::eLanguageTypeSwift));
  @@ -1558,6 +1573,10 @@ lldb::TypeSystemSP SwiftASTContext::CreateInstance(lldb::LanguageType language,
  }
  }
  + // Skip images without a serialized Swift AST.
  + if (!HasSwiftModules(*module_sp))
  + return;
  +
  SymbolVendor *sym_vendor = module_sp->GetSymbolVendor();
  if (sym_vendor) {
  