ART: Refactor frontend.cc
ART: Refactor frontend.cc

Refactor frontend.cc. Pull out flags, merge them in arrays keyed by
the instruction set. Simplify the checks and application of flags.

Change-Id: I12d5216df8d1f12e7fbe39d8132e4725c55bc8e7

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst