bit_foreach_unset_at
bit_foreach_unset_at(_bitstr, /*start*/0, _nbits, _iter)
BITSTRING_TC_DEFINE(bit_foreach_unset_at)
bit_foreach_unset_at(bitstr, nbits, nbits, unset_bit) {
bit_foreach_unset_at(bitstr, s, nbits, unset_bit) {
bit_foreach_unset_at(bitstr, 0, e, unset_bit) {
BITSTRING_TC_ADD(tp, bit_foreach_unset_at);