samples: add Terra samples

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

samples/Terra/linkllvm.t

@@ -0,0 +1,13 @@
+
+
+terra add(a : int, b : int)
+    return a + b
+end
+
+
+terralib.saveobj("add.bc",{ add = add })
+
+local addlib = terralib.linkllvm("add.bc")
+add2 = addlib:extern("add", {int,int} -> int)
+
+assert(add2(3,4) == 7)