* Implement both RawSPU and threaded SPU page fault recovery
* Guard page_fault_notification_entries access with a mutex
* Add missing lock in sys_ppu_thread_recover_page_fault/get_page_fault_context
* Fix EINVAL check in sys_ppu_thread_recover_page_fault, previously when the event was not found begin() was erased and
CELL_OK was returned.
* Fixed page fault recovery waiting logic:
- Do not rely on a single thread_ctrl notification (unsafe)
- Avoided a race where ::awake(ppu) can be called before ::sleep(ppu) therefore nop-ing out the notification
* Avoid inconsistencies with vm flags on page fault cause detection
* Fix sys_mmapper_enable_page_fault_notification EBUSY check
from RE it's allowed to register the same queue twice (on a different area) but not to enable page fault notifications twice
Implement helper functions balanced_wait_until and balanced_awaken
They include new path for Windows 8.1+ (WaitOnAddress)
shared_mutex, cond_variable, cond_one, cond_x16 modified to use it
Added helper function utils::popcnt16
Replace most semaphore<> with shared_mutex
