ART: Move JNI files to runtime/jni/ .

Test: Rely on TreeHugger.
Change-Id: I9cae11191ef1567ae9453be498882a7767285140
diff --git a/runtime/native/java_lang_Thread.cc b/runtime/native/java_lang_Thread.cc
index 9a52f70..9edb0c2 100644
--- a/runtime/native/java_lang_Thread.cc
+++ b/runtime/native/java_lang_Thread.cc
@@ -17,7 +17,7 @@
 #include "java_lang_Thread.h"
 
 #include "common_throws.h"
-#include "jni_internal.h"
+#include "jni/jni_internal.h"
 #include "mirror/object.h"
 #include "monitor.h"
 #include "native_util.h"