message: Fix GetLibrarySearchPaths so it doesn't add empty strings in the
  middle of the path list.
diff: @@ -3390,9 +3390,8 @@ static void
  GetLibrarySearchPaths(std::vector<std::string> &paths,
  const swift::SearchPathOptions &search_path_opts) {
  paths.clear();
  - paths.resize(search_path_opts.LibrarySearchPaths.size() + 1);
  - std::copy(search_path_opts.LibrarySearchPaths.begin(),
  - search_path_opts.LibrarySearchPaths.end(), paths.begin());
  + paths.assign(search_path_opts.LibrarySearchPaths.begin(),
  + search_path_opts.LibrarySearchPaths.end());
  paths.push_back(search_path_opts.RuntimeLibraryPath);
  }
  