fix GC safety issue in bootimage.cpp
fix GC safety issue in bootimage.cpp

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