[CRIU] [PATCH 0/15] restorer: Sanitize sigreturn_restore()

[Pavel Emelyanov]

This routine has grown too big and messy, since lots of
stuff require task_restore_args (and thread_restore_args)
to be at hands. Sometimes it's handled by keeping the
needed data somewhere and then copying it into restorer,
sometimes by patching talis of sigreturn_restore.

This set makes first step towards making sigreturn_restore()
being small and doing one thing -- prepare restorer memory
layout and jumping into restorer blob. The step is -- make
task and thead args be ready as early as required.