....but it seems makefile.mk file is missing from the distro...

Yes, support for dmake (which is the make "flavour" for which the makefile.mk was written) has been withdrawn.
Use "GNU make" (aka "gmake", but sometimes simply called "make") instead. It will use GNUmakefile.

The build options are the same for GNUmakefile as they were with makefile.mk so you shouldn't have too many alterations to make to your existing batch file.
But it will have to be altered to call GNU make instead of dmake.

Cheers,
Rob