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
diff --git a/runtime/gc/space/image_space.h b/runtime/gc/space/image_space.h
index 54dc7a6..93ff8aa 100644
--- a/runtime/gc/space/image_space.h
+++ b/runtime/gc/space/image_space.h
@@ -152,6 +152,10 @@
   // the ClassLinker during it's initialization.
   std::unique_ptr<OatFile> oat_file_;
 
+  // There are times when we need to find the boot image oat file. As
+  // we release ownership during startup, keep a non-owned reference.
+  const OatFile* oat_file_non_owned_;
+
   const std::string image_location_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageSpace);