ART: Clean up includes.

Reduce dependencies to improve incremental build times.
Break up circular dependency involving class_linker-inl.h.

Change-Id: I4be742c5c2b5cd9855beea86630fd68aab76b0db
diff --git a/compiler/oat_writer.cc b/compiler/oat_writer.cc
index 5b4cc54..804e4c1 100644
--- a/compiler/oat_writer.cc
+++ b/compiler/oat_writer.cc
@@ -36,6 +36,7 @@
 #include "mirror/art_method-inl.h"
 #include "mirror/array.h"
 #include "mirror/class_loader.h"
+#include "mirror/dex_cache-inl.h"
 #include "mirror/object-inl.h"
 #include "os.h"
 #include "output_stream.h"