ART: Move JNI files to runtime/jni/ .

Test: Rely on TreeHugger.
Change-Id: I9cae11191ef1567ae9453be498882a7767285140
diff --git a/runtime/hidden_api_test.cc b/runtime/hidden_api_test.cc
index 68d4eec..ab0c290 100644
--- a/runtime/hidden_api_test.cc
+++ b/runtime/hidden_api_test.cc
@@ -17,7 +17,7 @@
 #include "hidden_api.h"
 
 #include "common_runtime_test.h"
-#include "jni_internal.h"
+#include "jni/jni_internal.h"
 #include "proxy_test.h"
 
 namespace art {