ART: Fix CFI test wrt/ PIC

PIC boot images can't be loaded with dlopen, as their base is zero,
but we have an expectant address. Turn off in-process unwinding
in 137-cfi by checking the boot image oat file type.

Keep a non-owned referenced to the oat file in image space to simplify
access.

Change-Id: Ia2b525f9b2ecbc80b433f09e04ebece4cb6f2d2b