Added struct lifetime test

tests/programs/struct-lifetime.q

@@ -0,0 +1,8 @@
+main() {
+	c := new(Counter)
+	c.value += 16
+}
+
+struct Counter {
+	value int
+}

tests/programs_test.go

@@ -69,6 +69,7 @@ var programs = []struct {
 	{"index-static", 0},
 	{"index-dynamic", 0},
 	{"struct", 0},
+	{"struct-lifetime", 0},
 	{"len", 0},
 	{"cast", 0},
 	{"function-pointer", 0},