Initial implementation of the thread initialization

xtoskrnl/includes/amd64/kepfuncs.h

@@ -28,6 +28,14 @@ XTAPI
 VOID
 KepArchInitialize(VOID);
 
+XTAPI
+VOID
+KepInitializeThreadContext(IN PKTHREAD Thread,
+                           IN PKSYSTEM_ROUTINE SystemRoutine,
+                           IN PKSTART_ROUTINE StartRoutine,
+                           IN PVOID StartContext,
+                           IN PCONTEXT ContextRecord);
+
 XTAPI
 VOID
 KepStartKernel(VOID);