VOID
PopSetPerfFlag(
  IN  ULONG   PerfFlag,
  IN  BOOLEAN Clear
  );

Routine Description:

    There are certain times when we want to set certain flags for each
    processor. This function will safely set or clear the specified flag

Arguments:

    PerfFlag    - The bits to set or clear
    Clear       - Should we set or clear

Return Value:

    None        - We can't return the old flag because they are allowed to
                  vary in the case that its an MP system...