Remove make-tapreg-dotc and its uses, since Python is now mandatory

Change-Id: I13fd57a288be68d18819826bf566ed7b5688ebaa
Reviewed-on: https://code.wireshark.org/review/3926
Reviewed-by: Evan Huus <eapache@gmail.com>
Petri-Dish: Evan Huus <eapache@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Graham Bloice <graham.bloice@trihedral.com>