art: use proper nativehelper headers

libnativeheader exports headers under nativeheader. These were
available before incorrectly as global headers in order to give
access to jni.h.

Test: modules using art find headers
Bug: 63762847
Change-Id: I5c820d677e94e07b2859e78610bc997fe51b41dc
diff --git a/runtime/native/java_lang_Thread.cc b/runtime/native/java_lang_Thread.cc
index 4ce72ed..4fbbb72 100644
--- a/runtime/native/java_lang_Thread.cc
+++ b/runtime/native/java_lang_Thread.cc
@@ -16,16 +16,15 @@
 
 #include "java_lang_Thread.h"
 
-#include "nativehelper/jni_macros.h"
-
 #include "common_throws.h"
 #include "jni_internal.h"
-#include "monitor.h"
 #include "mirror/object.h"
+#include "monitor.h"
 #include "native_util.h"
+#include "nativehelper/jni_macros.h"
+#include "nativehelper/ScopedUtfChars.h"
 #include "scoped_fast_native_object_access-inl.h"
 #include "scoped_thread_state_change-inl.h"
-#include "ScopedUtfChars.h"
 #include "thread.h"
 #include "thread_list.h"
 #include "verify_object.h"