Fix maxlinelen

Summary: Fix fgets to read up to `length -1` instead of `length`
Also fix `SplFileObject::fgets` to include the `maxLineLen`

I moved all good tests found in `standard/file`
`fgetss_basic2.php` `fgetss_variant3.php` are fixed by this diff.

Closes https://github.com/facebook/hhvm/pull/3553

Reviewed By: @ptarjan

Differential Revision: D1512238