pidgin: allowed to build without avahi or gnutls

gnome2/pidgin/pidgin.conf

@@ -13,7 +13,10 @@
 # --- SDE-COPYRIGHT-NOTE-END ---
 
 var_append confopt ' ' "--disable-schemas-install"
-# we don't have meanwhile packaged yet
-var_append confopt ' ' '--disable-meanwhile'
-# we don't have NetworkManager yet
-var_append confopt ' ' '--disable-nm'
+
+# we don't have meanwhile, NetworkManager or nss yet
+for x in meanwhile nm avahi nss gnutls; do
+	if ! pkginstalled "$x"; then
+		var_append extraconfopt ' ' "--disable-$x"
+	fi
+done