ART: Add pic flag to oat header store

Add the compile-time PIC flag to the oat-header key-value store.
Ignore image offset and patch delta when loading PIC oat files.

Change-Id: Ie1f1ef37125386a968228033d1e2bec565315510
diff --git a/runtime/oat_file.h b/runtime/oat_file.h
index 734b9b3..ad6871d 100644
--- a/runtime/oat_file.h
+++ b/runtime/oat_file.h
@@ -72,6 +72,8 @@
     return is_executable_;
   }
 
+  bool IsPic() const;
+
   ElfFile* GetElfFile() const {
     CHECK_NE(reinterpret_cast<uintptr_t>(elf_file_.get()), reinterpret_cast<uintptr_t>(nullptr))
         << "Cannot get an elf file from " << GetLocation();