[FIX] Genie:  10.8 compile fix
relix:  Rename "schedule" unit to checkpoint_delta
Genie -> relix:  Move scheduler; process -> thread

The mark_foo_{,in}active() functions actually operate on thread ids, not
process ids, so name them appropriately.
Genie:  Fix use of mark_thread_{,in}active()

Be consistent and pass thread ids, not process ids.
Genie:  Inline Process::ResetSignalAction()
Genie:  Inline Process::DeliverSignal() -> Raise()
Genie:  Simplify signal action reset

We don't need to bounds-check the signal number (since it's generated by
a loop we control) and we've already checked for SIG_IGN.
Genie:  Hoist SIG_IGN check up to sigaction()

Move the clear_pending_signal() out of SetSignalAction() and also remove
the redundant signo bounds checks.
Genie:  Avoid Process use in sigaction()
Genie:  Axe obsolete Process::SetSignalAction()
Merge branch 'sigaction-cleanup'