make: Switch main Makefile to simplified form

This is a bit tricky since the build infrastructure
we're switching to is targeted to per-directory targets
if simplified Makefiles are used.

So I did the following

 - move rules to compile general sources to Makefile.crtools
 - main Makefiles now simply calls for scritps/Makefile.build
   help to generate built-in.o target

Also note that we clean up suffixes for implicit rules with

	.SUFFIXES:

this is done on purpose to eliminate any possible side effect
in future -- all rules _must_ be described explicitly.

Because of implicit rules used in zdtm building procedure
I can't use of stict makefile mode and add

	MAKEFLAGS := -r

to the top of the general Makefile. This should be done
one day latter (if ever).

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>