Remove ExtractCodeAndPrelink and switch Portable to MCLinker

Change-Id: Ia2459c7da6b79e0a1c0f1148c6e28ad9cbbe27a2
diff --git a/src/image_writer.cc b/src/image_writer.cc
index d9ac61b..ad2c9b7 100644
--- a/src/image_writer.cc
+++ b/src/image_writer.cc
@@ -78,7 +78,7 @@
     LOG(ERROR) << "Failed to open oat file " << oat_filename << " for " << oat_location;
     return false;
   }
-  oat_file_ = OatFile::Open(oat_file.get(), oat_location, NULL, true);
+  oat_file_ = OatFile::OpenWritable(oat_file.get(), oat_location);
   class_linker->RegisterOatFile(*oat_file_);
 
   {