longest_match
s->match_length = longest_match (s, hash_head);
s->match_length = longest_match (s, hash_head);
s->match_length = longest_match (s, hash_head);
s->match_length = longest_match (s, hash_head);
uInt longest_match(deflate_state *s, IPos cur_match);
local uInt longest_match(deflate_state *s, IPos cur_match);