fix Value::home integer overflow
fix Value::home integer overflow

A method with a large number of local variable slots may imply offsets
larger than a int8_t can represent, so we now use an int16_t instead.

marcinolawski/avian,getlantern/avian,dicej/avian,bigfatbrowncat/avian-pack.avian,dicej/avian,lwahlmeier/avian,bigfatbrowncat/avian-pack.avian,bgould/avian,getlantern/avian,ucdseniordesign/avian,ucdseniordesign/avian,dicej/avian,ucdseniordesign/avian,joshuawarner32/avian,badlogic/avian,badlogic/avian,MaartenR/avian,badlogic/avian,bgould/avian,MaartenR/avian,getlantern/avian,ucdseniordesign/avian,bigfatbrowncat/avian-pack.avian,dicej/avian,marcinolawski/avian,lostdj/avian,minor-jason/avian,lwahlmeier/avian,minor-jason/avian,lostdj/avian,joshuawarner32/avian,marcinolawski/avian,bgould/avian,joshuawarner32/avian,marcinolawski/avian,bigfatbrowncat/avian-pack.avian,lostdj/avian,badlogic/avian,bgould/avian,lwahlmeier/avian,MaartenR/avian,MaartenR/avian,lwahlmeier/avian,joshuawarner32/avian,minor-jason/avian,lostdj/avian,getlantern/avian,minor-jason/avian