Detach the calling thread from this JVM

Property definitions

jvm $ JavaVM :: detach_current_thread
	# Detach the calling thread from this JVM
	fun detach_current_thread import jni_error `{
		int res = (*self)->DetachCurrentThread(self);
		if (res != JNI_OK) {
			JavaVM_jni_error(NULL, "Could not detach current thread to Java VM", res);
		}
	`}
lib/jvm/jvm.nit:204,2--210,3