- Scheduler was increasing total priorities only when resuming tasks had 0 ticks.
This caused forked tasks that have parent's share of ticks to finish their jobs,
if these tasks exited quick enough, they would cause the total priorities to deduce
without increasing it in the first place. This is now fixed.
- Also strengthened rq locking, now both queues are locked before touching any.
- Also removed task suspends in irq, this would cause a race condition on ticks and
runqueues, since neither is protected against irqs.
- Implemented reasonable way to suspend task.
- A task that has a pending suspend would be interrupted
from its sleep via the suspender task.
- If suspend was raised and right after, task became about to sleep,
then scheduler wakes it up.
- If suspend was raised when task was in user mode, then an irq suspends it.
- Also suspends are checked at the end of a syscall so that if suspend was
raised because of a syscall from the task, the task is suspended before it
goes back to user mode.
- This mechanism is very similar to signals, and it may lead as a base for
implementing signal handling.
- Implemented common vma dropping for shadow vm object dropping and task exiting.
