Use line feed character for EOF newline

As far as I know, `JSON.stringify(json, null, 2)` uses LF character for line endings in every platforms. [Specification](http://www.ecma-international.org/ecma-262/5.1/#sec-15.12.3) said:

> Let separator be the result of concatenating the comma character, the ***line feed character***, and indent.

So, fixpack should use line feed character for EOF newline.