Each time I type `make clean` and find that my tags are cleaned
and generated headers/c-files are deleted, I'm getting annoyed.
Mostly it's about protobuf images definitions.
(And then I need to run `make` and `make tags` again which
is painful).

I think, we may separate clean process on two parts, just
like it's done in the kernel (omitting distclean):
 o Cleaning all binaries/objects, but leave enough to navigate
 o Clean everything compiled/generated/etc.

In this patch pie blobs are still deleted on clean stage - I may
fix it in the later patches.
(they _should_ be regenerated on `make clean && make`)

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>