samples: add Terra samples

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

samples/Terra/fnpointer.t

@@ -0,0 +1,24 @@
+
+terra foo()
+    return 4LL
+end
+
+terra bar()
+    return 5LL
+end
+
+terra bar3(fn: {} -> int64)
+	return fn()
+end
+
+terra baz(a : int64)
+    var afn = foo
+    if a > 2 then
+       afn = bar
+    end
+    return bar3(afn)
+end
+
+local test = require("test")
+test.eq(baz(1),4)
+test.eq(baz(3),5)