Call madvise hints for image dex files

After opening image spaces, perform madvise hints for the
corresponding dex files.

Moved kMadviseDexFileAccesses to oat_file.cc to not have this enabled
yet.

Bug: 63178181
Test: make and flash

(cherry picked from commit 3efecdef520e80cd79f34549c4ba3a77042d0d92)

Change-Id: If91537e098b159d00354551ce6400a806549b2ca
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 0efc004..051c0c2 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -1021,6 +1021,9 @@
                            std::make_move_iterator(dex_files.begin()),
                            std::make_move_iterator(dex_files.end()));
   }
+  for (const std::unique_ptr<const DexFile>& dex_file : boot_dex_files_) {
+    OatDexFile::MadviseDexFile(*dex_file, MadviseState::kMadviseStateAtLoad);
+  }
   FinishInit(self);
 
   VLOG(startup) << __FUNCTION__ << " exiting";