Revert "ART: Key-Value Store in Oat header"

Broke arm64 build.

This reverts commit c87d27b25994da8670d82a8f7bad6327b693bfff.

Change-Id: I4c2ade295d2b5aa77fc3ad810e0e859629a5bf09
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 0e4028b..60453c3 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -1163,9 +1163,7 @@
   OatFile& oat_file = GetImageOatFile(space);
   CHECK_EQ(oat_file.GetOatHeader().GetImageFileLocationOatChecksum(), 0U);
   CHECK_EQ(oat_file.GetOatHeader().GetImageFileLocationOatDataBegin(), 0U);
-  const char* image_file_location = oat_file.GetOatHeader().
-      GetStoreValueByKey(OatHeader::kImageLocationKey);
-  CHECK(image_file_location == nullptr || *image_file_location == 0);
+  CHECK(oat_file.GetOatHeader().GetImageFileLocation().empty());
   portable_resolution_trampoline_ = oat_file.GetOatHeader().GetPortableResolutionTrampoline();
   quick_resolution_trampoline_ = oat_file.GetOatHeader().GetQuickResolutionTrampoline();
   portable_imt_conflict_trampoline_ = oat_file.GetOatHeader().GetPortableImtConflictTrampoline();