Revert "Refactor mkFlag out of old packages"

This reverts commit 3117e0c897.

Conflicts:
	pkgs/development/libraries/wayland/default.nix
	pkgs/servers/samba/4.x.nix

pkgs/tools/filesystems/ceph/generic.nix

@@ -28,6 +28,13 @@ assert cryptopp != null || (nss != null && nspr != null);
 
 with stdenv.lib;
 let
+  mkFlag = trueStr: falseStr: cond: name: val:
+    if cond == null then null else
+      "--${if cond != false then trueStr else falseStr}${name}${if val != null && cond != false then "=${val}" else ""}";
+  mkEnable = mkFlag "enable-" "disable-";
+  mkWith = mkFlag "with-" "without-";
+  mkOther = mkFlag "" "" true;
+
   hasServer = snappy != null && leveldb != null;
   hasMon = hasServer;
   hasMds = hasServer;