ART: Small class-inl.h cleanup

Remove unnecessary class_linker-inl.h include, and fix up all
transitives (mainly gc_root-inl.h). Also clean up reference.h.

Test: m test-art-host
Change-Id: I47bd6edcfe4a23821e37a6e6fa8cca91d0d2d226
diff --git a/runtime/gc/heap_verification_test.cc b/runtime/gc/heap_verification_test.cc
index 2cdfc16..a307c51 100644
--- a/runtime/gc/heap_verification_test.cc
+++ b/runtime/gc/heap_verification_test.cc
@@ -17,7 +17,7 @@
 #include "common_runtime_test.h"
 
 #include "base/memory_tool.h"
-#include "class_linker.h"
+#include "class_linker-inl.h"
 #include "handle_scope-inl.h"
 #include "mirror/object-inl.h"
 #include "mirror/object_array-inl.h"