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/core/jni/android_hardware_SoundTrigger.cpp b/core/jni/android_hardware_SoundTrigger.cpp
index 0c7f5a1..9dbb8d7 100644
--- a/core/jni/android_hardware_SoundTrigger.cpp
+++ b/core/jni/android_hardware_SoundTrigger.cpp
@@ -20,7 +20,7 @@
 #include <utils/Log.h>
 
 #include "jni.h"
-#include "JNIHelp.h"
+#include <nativehelper/JNIHelp.h>
 #include "core_jni_helpers.h"
 #include <system/sound_trigger.h>
 #include <soundtrigger/SoundTriggerCallback.h>