samples: add Terra samples

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

samples/Terra/multimacro.t

@@ -0,0 +1,17 @@
+
+local bar = terralib.internalmacro(function(ctx,tree,typ,x)
+	return {terralib.newtree(typ.tree, { kind = terralib.kinds.literal, type = double, value = 4.0 }), x }
+end)
+
+local x,y,z = 1,2,3
+
+terra foo() : int
+	var a,b = bar(int,x + y + z)
+	var c = bar(int,0)._0 + 1
+	--bar2(int) = bar2(int) + 5
+	--bar3(up(&a),up(&a))
+	return a + b + c
+end
+
+local test = require("test")
+test.eq(15,foo())