Use the length operator (#) instead of table.getn.

table.getn was deprecated in Lua 5.1 in favor of #, the length operator.
See: http://www.lua.org/manual/5.1/manual.html#7.2

test/urltest.lua

@@ -34,7 +34,7 @@ end
 
 local check_parse_path = function(path, expect)
     local parsed = socket.url.parse_path(path)
-    for i = 1, math.max(table.getn(parsed), table.getn(expect)) do
+    for i = 1, math.max(#parsed, #expect) do
         if parsed[i] ~= expect[i] then
             print(path)
             os.exit()