This function only reads the data being referenced, it doesn't modify
it, so we can turn the reference into a const reference.

This function isn't used outside of this translation unit, so we can
make it internally linked.

Removes unnecessary direct dependencies in some headers and also gets
rid of indirect dependencies that were being relied on to be included.

Note that there's currently a dynarmic bug preventing this register from being written.

Makes the thread status strongly typed, so implicit conversions can't
happen. It also makes it easier to catch mistakes at compile time.

Avoids pointless copies

This would result in a lot of allocations and related object
construction, just to toss it all away immediately after the call.

These are definitely not intentional, and it was intended that all of
these should have been accessing the static function GetInstance()
through the name itself, not constructed instances.

Kernel/Threads: A thread waking up by timeout from a WaitProcessWideKey may already have an assigned lock owner.

This situation may happen like so:
Thread 1 with low priority calls WaitProcessWideKey with timeout.
Thread 2 with high priority calls WaitProcessWideKey without timeout.
Thread 3 calls SignalProcessWideKey
- Thread 2 acquires the lock and awakens.
- Thread 1 can't acquire the lock and is put to sleep with the lock owner being Thread 2.
Thread 1's timeout expires, with the lock owner still being set to Thread 2.

All of these variables and functions are related to timings and should be within the namespace.

Verified with a hwtest and implemented based on reverse engineering.

Thread A's priority will get bumped to the highest priority among all the threads that are waiting for a mutex that A holds.
Once A releases the mutex and ownership is transferred to B, A's priority will return to normal and B's priority will be bumped.

Switch mutexes are no longer kernel objects, they are managed in userland and only use the kernel to handle the contention case.
Mutex addresses store a special flag value (0x40000000) to notify the guest code that there are still some threads waiting for the mutex to be released. This flag is updated when a thread calls ArbitrateUnlock.

TODO:
* Fix svcWaitProcessWideKey
* Fix svcSignalProcessWideKey
* Remove the Mutex class.

Ported from citra PR #3091

The delay specified here is from a Nintendo 3DS, and should be measured in a Nintendo Switch.

This change is enough to prevent Puyo Puyo Tetris's main thread starvation.

* CoreTiming: New CoreTiming; Add Test for CoreTiming