JNIHelp.h
is not part of NDK. You inherited some code from the Android platform. You will find other dependencies on non-public modules, most likely libcutils and libutils.
You have three options: build your code as a module of the platform, rewrite the code to only use public headers and libraries, or download parts of the platform, e.g. https://android.googlesource.com/platform/libnativehelper/, and arrange the include paths accordingly.
To satisfy the linker in the latter scenario, you can use adb pull /system/lib
to acquire the versions of libnativehelper.so
, libcutils.so
, and other referenced non-public libraries. Note that ndk-build will complain about linking against these libraries.