blockcheck2: graceful shutdown on QUIT signal

blockcheck2.sh

@@ -1916,6 +1916,7 @@ trap sigint INT
 trap sigsilent PIPE
 trap sigsilent HUP
 trap sigsilent TERM
+trap sigsilent QUIT
 for dom in $DOMAINS; do
 	for IPV in $IPVS; do
 		configure_ip_version
@@ -1929,6 +1930,7 @@ for dom in $DOMAINS; do
 		[ "$ENABLE_HTTP3" = 1 ] && check_domain_http3 $dom
 	done
 done
+trap - QUIT
 trap - TERM
 trap - HUP
 trap - PIPE