samples: add Terra samples

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

samples/Terra/unsafesym.t

@@ -0,0 +1,14 @@
+
+local mymacro = macro(function(a)
+    a = a:asvalue()
+    print(a, terralib.issymbol(a), terralib.unsafetypeofsymbol(a))
+    return {}
+end)
+
+
+
+terra foo(a : int)
+    mymacro(a)
+end
+
+foo:compile()