Kernel: Make spinlocks more safe

Kernel now makes sure thread is not holding any spinlocks when it tries
to lock a mutex or yield. Spinlocks are supposed to be only used for
short times without the possibility of yielding

kernel/kernel/Processor.cpp

@@ -337,6 +337,8 @@ namespace Kernel
 		auto state = get_interrupt_state();
 		set_interrupt_state(InterruptState::Disabled);
 
+		ASSERT(!Thread::current().has_spinlock());
+
 		auto& processor_info = s_processors[current_id().as_u32()];
 
 		{