Now we build only what we really need for 'build' platform - there is
new build-tools make target.
The list of tools is in solenv/gbuild/extensions/pre_BuildTools.mk.
Also similar is done to some extent for 'host' platform using
gb_Module_add_targets_for_build which is ignored for 'host'.

Change-Id: I6acd1762b16aca366aac1a0688500f27869cfca2