Add pipeline support

  Define class Proc with UniCoreGenericItineraries template argument so that
we can use instruction itinerary classes defined in UniCoreSchedule.td in
UniCoreInstrFormats.td and UniCoreInstrInfo.td. Also, add pipeline related
data members and member functions in UniCoreSubtarget and UniCoreTargetMachine.

Signed-off-by: Chen Wei-Ren <chenwj@iis.sinica.edu.tw>