samples: add Terra samples

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

samples/Terra/vars2.t

@@ -0,0 +1,17 @@
+
+a = global(int) --testing variable with no initializer
+
+
+terra foo()
+	a = 3
+end
+
+terra bar()
+	return a
+end
+
+
+local test = require("test")
+
+foo()
+test.eq(bar(),3)