Rework initial timer support

xtoskrnl/includes/kei.h

@@ -17,6 +17,10 @@ XTAPI
 VOID
 KeClearEvent(IN PKEVENT Event);
 
+XTAPI
+VOID
+KeClearTimer(IN PKTIMER Timer);
+
 XTAPI
 VOID
 KeHaltSystem(VOID);
@@ -78,6 +82,14 @@ XTAPI
 VOID
 KeStartXtSystem(IN PKERNEL_INITIALIZATION_BLOCK Parameters);
 
+XTFASTCALL
+VOID
+KepExitDispatcher(IN KRUNLEVEL OldRunLevel);
+
+XTAPI
+VOID
+KepRemoveTimer(IN OUT PKTIMER Timer);
+
 XTFASTCALL
 VOID
 KepRetireDpcList(IN PKPROCESSOR_CONTROL_BLOCK Prcb);