ncd: tests: add call.ncd

ncd/tests/call.ncd

@@ -0,0 +1,18 @@
+process main {
+    var("bad_x") x;
+    var("good_x") y;
+    call("helper_func", {}) helper;
+    call_with_caller_target("func1", {}, "helper") c;
+    val_equal(c.x, "good_x") a;
+    assert(a);
+    
+    exit("0");
+}
+
+template helper_func {
+    var(_caller.y) x;
+}
+
+template func1 {
+    var(_caller.x) x;
+}