STREAM_END_SPACE
def_strm.avail_out += STREAM_END_SPACE;
if (*dstlen <= STREAM_END_SPACE)
while (def_strm.total_out < *dstlen - STREAM_END_SPACE && def_strm.total_in < *sourcelen) {
def_strm.avail_out = *dstlen - (def_strm.total_out + STREAM_END_SPACE);