samples: add Terra samples

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

samples/Terra/cnamespace.t

@@ -0,0 +1,24 @@
+G,T = terralib.includecstring [[
+    typedef struct {
+        double c;
+    } A;
+    struct A {
+        int b;
+    };
+]]
+
+G2,T2 = terralib.includecstring [[
+    struct A;
+    typedef struct C A;
+]]
+
+assert(T2.A == T.A)
+assert(G2.A ~= T2.A and G2.A ~= G.A)
+terra foo()
+    var a : G.A
+    var b : T.A
+    a.c = 4.5
+    b.b = 4.5
+    return a.c + b.b
+end
+assert(8.5 == foo())