CLEANUP: tcpcheck: use pool_zalloc() instead of pool_alloc+memset

Two places used to alloc then zero the area, let's have the allocator do it.
diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index 90f1ee9..52b47ee 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -3618,9 +3618,8 @@
 	struct tcpcheck_rule *tcpcheck, *prev_check;
 	struct tcpcheck_expect *expect;
 
-	if ((tcpcheck = pool_alloc(pool_head_tcpcheck_rule)) == NULL)
+	if ((tcpcheck = pool_zalloc(pool_head_tcpcheck_rule)) == NULL)
 		return 0;
-	memset(tcpcheck, 0, sizeof(*tcpcheck));
 	tcpcheck->action = TCPCHK_ACT_EXPECT;
 
 	expect = &tcpcheck->expect;
@@ -3661,9 +3660,8 @@
 	char *dst;
 	int i;
 
-	if ((tcpcheck = pool_alloc(pool_head_tcpcheck_rule)) == NULL)
+	if ((tcpcheck = pool_zalloc(pool_head_tcpcheck_rule)) == NULL)
 		return 0;
-	memset(tcpcheck, 0, sizeof(*tcpcheck));
 	tcpcheck->action       = TCPCHK_ACT_SEND;
 
 	send = &tcpcheck->send;