When increasing the base priority at shutdown, acquire the necessary
SE_INC_BASE_PRIORITY_PRIVILEGE in CsrSetToShutdownPriority(),
called by CsrShutdownProcesses(), which is necessary due to the increase
of process base priority (i.e. increase of scheduling) being done.
Dedicated to George Bișoc :)
The Shutdown privilege is however unnecessary (or unwanted) since this
has been already dealt with by the shutdown caller. Also, it will be
needed only by the caller of NtShutdownSystem() -- that we don't call
at all here.