libpacman: Vectorise _pacman_db_get_grpfromcache in _pacman_db_get_grpfromlist to allow simplification of _pacman_db_load_grpcache (avoiding multiple dummy iterations and assumption on Package::name layout).
libpacman: Previous commits removed broken pointers access to libpacman::Group, so it can be a proper ::flib::FObject now.