[kutil] Update spinlock to an MCS-style lock

Update the existing but unused spinlock class to an MCS-style queue
spinlock. This is probably still a WIP but I expect it to see more use
with SMP getting further integrated.

modules.yaml

@@ -114,6 +114,7 @@ modules:
             - src/libraries/kutil/logger.cpp
             - src/libraries/kutil/memory.cpp
             - src/libraries/kutil/printf.c
+            - src/libraries/kutil/spinlock.cpp
 
     cpu:
         kind: lib