Kernel: Stop using HashMap in Mutex

This commit removes the usage of HashMap in Mutex, thereby making Mutex
be allocation-free.

In order to achieve this several simplifications were made to Mutex,
removing unused code-paths and extra VERIFYs:
 * We no longer support 'upgrading' a shared lock holder to an
   exclusive holder when it is the only shared holder and it did not
   unlock the lock before relocking it as exclusive. NOTE: Unlike the
   rest of these changes, this scenario is not VERIFY-able in an
   allocation-free way, as a result the new LOCK_SHARED_UPGRADE_DEBUG
   debug flag was added, this flag lets Mutex allocate in order to
   detect such cases when debugging a deadlock.
 * We no longer support checking if a Mutex is locked by the current
   thread when the Mutex was not locked exclusively, the shared version
   of this check was not used anywhere.
 * We no longer support force unlocking/relocking a Mutex if the Mutex
   was not locked exclusively, the shared version of these functions
   was not used anywhere.

Kernel/Debug.h.in

@@ -182,6 +182,10 @@
 #cmakedefine01 LOCK_RESTORE_DEBUG
 #endif
 
+#ifndef LOCK_SHARED_UPGRADE_DEBUG
+#cmakedefine01 LOCK_SHARED_UPGRADE_DEBUG
+#endif
+
 #ifndef LOCK_TRACE_DEBUG
 #cmakedefine01 LOCK_TRACE_DEBUG
 #endif