samples: add Terra samples

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

samples/Terra/fastcall.t

@@ -0,0 +1,24 @@
+
+terra foo()
+	return 1
+end
+
+
+assert(1 == foo())
+assert(rawget(foo,"fastcall") == foo:getdefinitions()[1].ffiwrapper)
+assert(1 == foo())
+
+
+terra foo2()
+	return 1,2
+end
+local a,b = terralib.unpackstruct(foo2())
+assert(a == 1 and b == 2)
+assert(rawget(foo2,"fastcall") == foo2:getpointer())
+local a,b = unpackstruct(foo2())
+assert(a == 1 and b == 2)
+
+terra foo(a : int)
+end
+
+assert(rawget(foo,"fastcall") == nil)