SUBROUTINE HVHBVI - Call QCDINS hard subprocess routine

This replaces a dummy stub in HERWIG [1] which was originally used as event generation interface for the Monte Carlo generator for baryon number violating interactions HERBVI [2]. It is used in QCDINS to allow only IPROC values between 7500 and 7999. It calls the QCDINS main hard process generator QIHGEN.