BUG/MINOR: snapshots: leak of snapshots on deinit()

Free the snapshots on deinit() when they were initialized in a proxy
upon an error.

This was introduced by c55015e ("MEDIUM: snapshots: dynamically allocate
the snapshots").

Should be backported as far as 1.9.
diff --git a/src/haproxy.c b/src/haproxy.c
index c6f7394..e891eb0 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2620,6 +2620,8 @@
 		free(p->capture_name);
 		free(p->monitor_uri);
 		free(p->rdp_cookie_name);
+		free(p->invalid_rep);
+		free(p->invalid_req);
 		if (p->conf.logformat_string != default_http_log_format &&
 		    p->conf.logformat_string != default_tcp_log_format &&
 		    p->conf.logformat_string != clf_http_log_format)