* Makefile.in (CPP): New variable.

* Makefile.in (CPP): New variable.
	(src/Makefile): Edit CPP into src/Makefile.

        Bring mumbleclean targets into conformance with GNU coding standards.
	* Makefile.in (mostlyclean, clean): Separate these two; just have
	them pass the request to the subdirectory makefiles.
	(distclean): Pass the request down, and then get rid of the
	files configure built, and get rid of the Makefiles.
	(realclean): Pass the request down, and then do the same things
	distclean does.
	(uninstall, info, dvi): New targets.