samples: add Terra samples

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

samples/Terra/proxystruct.t

@@ -0,0 +1,19 @@
+local c = terralib.includecstring [[
+	#include <stdlib.h>
+	#include <stdio.h>
+]]
+
+
+struct Node {
+	next : &Node;
+	v : int;
+}
+
+terra foo()
+	var cur : &Node = [&Node](c.malloc(sizeof(Node)))
+	cur.v = 3
+	return cur.v
+end
+
+local test = require("test")
+test.eq(foo(),3)