hardware/libhardware: 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 hardware/libhardware find headers
Bug: 63762847
Change-Id: I94305b7ab189ca0f3f89f4d87be2b113857f461f
diff --git a/tests/keymaster/keymaster_test.cpp b/tests/keymaster/keymaster_test.cpp
index 3040a5c..e8fa990 100644
--- a/tests/keymaster/keymaster_test.cpp
+++ b/tests/keymaster/keymaster_test.cpp
@@ -33,7 +33,7 @@
 #define LOG_TAG "keymaster_test"
 #include <utils/Log.h>
 
-#include <UniquePtr.h>
+#include <nativehelper/UniquePtr.h>
 
 #include <hardware/keymaster0.h>