samples: add Terra samples

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

samples/Terra/symparam.t

@@ -0,0 +1,9 @@
+
+local a = symbol()
+terra foo([a] : int, b : int)
+	return [a] + b
+end
+
+local test = require("test")
+
+test.eq(foo(1,2),3)