com.android.server: 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: com.android.server finds headers
Bug: 63762847
Change-Id: Icb3018f520004f65e8dd565d6e1d563551548eba
diff --git a/services/core/jni/com_android_server_location_GnssLocationProvider.cpp b/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
index edd7d53..2b1225c 100644
--- a/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
+++ b/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
@@ -20,7 +20,7 @@
 
 #include <android/hardware/gnss/1.0/IGnss.h>
 
-#include "JNIHelp.h"
+#include <nativehelper/JNIHelp.h>
 #include "jni.h"
 #include "hardware_legacy/power.h"
 #include "utils/Log.h"