ART: Add object-readbarrier-inl.h

Move some read-barrier code into a new header. This prunes the
include tree for the concurrent-copying collector. Clean up other
related includes.

Test: mmma art
Change-Id: I40ce4e74f2e5d4c692529ffb4df933230b6fd73e
diff --git a/compiler/jni/jni_compiler_test.cc b/compiler/jni/jni_compiler_test.cc
index 21042a3..b34d938 100644
--- a/compiler/jni/jni_compiler_test.cc
+++ b/compiler/jni/jni_compiler_test.cc
@@ -27,6 +27,7 @@
 #include "dex_file.h"
 #include "gtest/gtest.h"
 #include "indirect_reference_table.h"
+#include "java_vm_ext.h"
 #include "jni_internal.h"
 #include "mem_map.h"
 #include "mirror/class-inl.h"