configure: add --disable-scfilter option

configure

@@ -115,6 +115,7 @@ For better control, use the options below.
   --disable-rtc          Don't include RTC even on Linux
   --disable-privdrop     Disable support for dropping root privileges
   --without-libcap       Don't use libcap even if it is available
+  --disable-scfilter     Disable support for system call filtering
   --without-seccomp      Don't use seccomp even if it is available
   --disable-asyncdns     Disable asynchronous name resolving
   --disable-forcednsretry Don't retry on permanent DNS error
@@ -322,12 +323,15 @@ do
     --without-libcap|--disable-linuxcaps)
       try_libcap=0
     ;;
-    --disable-asyncdns)
-      feat_asyncdns=0
+    --disable-scfilter)
+      feat_scfilter=0
     ;;
     --without-seccomp)
       try_seccomp=0
     ;;
+    --disable-asyncdns)
+      feat_asyncdns=0
+    ;;
     --disable-forcednsretry)
       feat_forcednsretry=0
     ;;