Always emit a jump in HhbcTranslator::endBlock

Summary: Otherwise, we can end up with mal-formed IR due to a block lacking a
fall-through.  If the fall-through offset doesn't belong to the
region, the fall-through jump will go to an exit block.

Reviewed By: @jdelong

Differential Revision: D1572617
Remove some random includes of ext_apc.h

Summary: Noticed these in some extension code that don't actually appear to use
APC.

Reviewed By: @jdelong

Differential Revision: D1574376