samples: add Terra samples

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

samples/Terra/decltwice.t

@@ -0,0 +1,18 @@
+
+terra mything
+
+terra mybar()
+	return mything(4)
+end
+
+terra mything(a : int)
+	return a
+end
+
+terra mything
+
+terra mybar2()
+	return mything(4)
+end
+
+assert(mybar() == mybar2())