samples: add Terra samples

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

samples/Terra/missingfields.t

@@ -0,0 +1,14 @@
+test = terralib.includecstring([[
+    typedef struct {} emptyanon;
+    typedef struct foo foobar;
+    void test(struct foo * f);
+    struct foo { int x; };
+    union ufoo;
+    typedef union { int a; int b; } anonunion;
+]])
+terra main()
+    var s : test.foo
+    s.x = 1
+end
+
+main()