jni_ vec_ sum
fun jni_vec_sum(env: CPointer<JNIEnvVar>, thisObject: jobject, a: jdoubleArray, aOffset: jint, aSize: jint): Double
fun jni_vec_sum(env: CPointer<JNIEnvVar>, thisObject: jobject, a: jdoubleArray, aOffset: jint, aSize: jint): Double