frameworks/base: 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 frameworks/base find headers
Bug: 63762847
Change-Id: I0f9f231acdebe460f279135462f43d3e32eff64d
diff --git a/services/core/jni/com_android_server_connectivity_tethering_OffloadHardwareInterface.cpp b/services/core/jni/com_android_server_connectivity_tethering_OffloadHardwareInterface.cpp
index 4e5c27f..87312f8 100644
--- a/services/core/jni/com_android_server_connectivity_tethering_OffloadHardwareInterface.cpp
+++ b/services/core/jni/com_android_server_connectivity_tethering_OffloadHardwareInterface.cpp
@@ -18,7 +18,7 @@
 #include <error.h>
 #include <hidl/HidlSupport.h>
 #include <jni.h>
-#include <JNIHelp.h>
+#include <nativehelper/JNIHelp.h>
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netlink.h>
 #include <sys/socket.h>