Add fibonacci to funcdefs.nct

tests/funcdefs.nct

@@ -1,7 +1,6 @@
-/* Currently return isn't implemented (and no ret instructions are output either) */
+fibonacci: u32(u32 n) -> {
-/* Oh and arguments aren't supported yet either */
+	if(n <= 1) {
-/* But functions work :) */
+		return n;
-
+	}
-foo: u0() {
+	return fibonacci(n - 1) + fibonacci(n - 2);
-	return 15;
 };