[BUG] appsession: possible memory leak in case of out of memory condition

I've tried to follow all the pool_alloc2/pool_free2 calls in the code
to track memory leaks. I've found one which only happens when there's
already no more memory when allocating a new appsession cookie.

diff --git a/src/proto_http.c b/src/proto_http.c
index fa8f557..0e5f324 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -5957,6 +5957,7 @@
 			if ((asession->sessid = pool_alloc2(apools.sessid)) == NULL) {
 				Alert("Not enough Memory process_srv():asession->sessid:malloc().\n");
 				send_log(t->be, LOG_ALERT, "Not enough Memory process_srv():asession->sessid:malloc().\n");
+				t->be->htbl_proxy.destroy(asession);
 				return;
 			}
 			memcpy(asession->sessid, t->sessid, t->be->appsession_len);
@@ -5966,6 +5967,7 @@
 			if ((asession->serverid = pool_alloc2(apools.serverid)) == NULL) {
 				Alert("Not enough Memory process_srv():asession->sessid:malloc().\n");
 				send_log(t->be, LOG_ALERT, "Not enough Memory process_srv():asession->sessid:malloc().\n");
+				t->be->htbl_proxy.destroy(asession);
 				return;
 			}
 			asession->serverid[0] = '\0';