But nobody uses it anyway, so clean up includes.

Wait/notify only on c_sig, should reduce spurious wakeup noise.

Add pointer comparison to notifiers (to prevent spurious wakeups).
Fix a bug with a possible double notification in raw_notify().
Fix a bug with incorrect allocatin bit slots for cond_handle.
Add a semaphore counter to track max allowed number of threads.
Use #define for some constants to STRINGIZE them in errors.
Add some error messages when certain limits are reached.
Fix a bug with a wrong check simply throwing std::abort.
Use "special" notify_all patch with batch processing for every arch.
Fix Win7 bug who no one probably noticed.

Add ref counters for internal semaphores for concurrent notifying.
Lack of them could result in loss of notification.

Only compare masks for overlap for second overload (with mask provided).
Explicit "new value" can be provided in new 3-arg overloads.
Also rename atomic_storage_futex -> atomic_wait_engine.