Themes: Use INSTALL_LOCATION_INTERNAL_ONLY for legacy icon packs

If an icon pack is currently applied and is installed using forward
locking, the system will crash when the pack is updated.  Several
applications can have the pack attached to their resources and this
causes the system to crash because it cannot unmount the asec container
to finish the post install process.  Installing these packs to internal
storage without forward locking alleviates this issue.

This is done with theme packs as well, including legacy themes.

Change-Id: I155fc0bd671f3f9baaf2565d1c4d654a0a5348dc