cpp: use proper nativehelper headers

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

Test: modules using cpp find headers
Bug: 63762847
Change-Id: I34722bb961327b0128703ab925bc86961ca66cb6
diff --git a/services/core/jni/com_android_server_UsbDescriptorParser.cpp b/services/core/jni/com_android_server_UsbDescriptorParser.cpp
index 98c5ec1..df85e31 100644
--- a/services/core/jni/com_android_server_UsbDescriptorParser.cpp
+++ b/services/core/jni/com_android_server_UsbDescriptorParser.cpp
@@ -18,7 +18,7 @@
 #include "utils/Log.h"
 
 #include "jni.h"
-#include "JNIHelp.h"
+#include <nativehelper/JNIHelp.h>
 
 #include <usbhost/usbhost.h>