[CRIU] [PATCH 0/3] CoreEntry allocation rework and lock code simplification

[Cyrill Gorcunov]

Quite soon I'll need CoreEntry items to be allocated early (for registers
preliminary dumping) and to use futexes in parasite code. But even
without the needs mentioned above I think this series makes code
more convenient to work with

 - no arbitrary coreentry allocations, all data bound to pstree item
 - BUG_ON code factored out for inclusion without the rest of already
   big util.h

Thus any of patch may be applied on its own, please take a look.