BUG/MINOR: proxy: missing free in free_proxy for redirect rules

cookie_str from struct redirect, which may be allocated through
http_parse_redirect_rule() function is not properly freed on proxy
cleanup within free_proxy().

This could be backported to all stable versions.

[for 2.2, free_proxy() did not exist so the fix needs to be performed
directly in deinit() function from haproxy.c]

src/proxy.c

@@ -243,6 +243,7 @@ void free_proxy(struct proxy *p)
 			free(rdr->cond);
 		}
 		free(rdr->rdr_str);
+		free(rdr->cookie_str);
 		list_for_each_entry_safe(lf, lfb, &rdr->rdr_fmt, list) {
 			LIST_DELETE(&lf->list);
 			release_sample_expr(lf->expr);