samples: add Terra samples

source: https://github.com/zdevito/terra/tree/master/tests

samples/Terra/structconstructor.t

@@ -0,0 +1,9 @@
+struct A { a : int, b : int}
+
+terra foobar()
+	var a = A { 3, 4}
+	return a.b
+end
+
+local test = require("test")
+test.eq(foobar(),4)