system/core: 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 system/core find headers
Bug: 63762847
Change-Id: I86240f7857dd815100cab32ad261aa9a0a54329c
diff --git a/gatekeeperd/SoftGateKeeperDevice.h b/gatekeeperd/SoftGateKeeperDevice.h
index 3463c29..229f9a9 100644
--- a/gatekeeperd/SoftGateKeeperDevice.h
+++ b/gatekeeperd/SoftGateKeeperDevice.h
@@ -19,7 +19,7 @@
 
 #include "SoftGateKeeper.h"
 
-#include <UniquePtr.h>
+#include <nativehelper/UniquePtr.h>
 
 using namespace gatekeeper;