Added missing code to increase attempts on file submission

Hi Dan,

I had problems with blocking files submission to Compilatio services for a long time, so I decided to dig a little bit, moodle code not being my daily cup of tea :-\

I found this missing lines of code under a comment that says "incrementing a counter", so after implementing them, the file submission queue began to fetch Compilatio services again.

I don't know the starting point of it all, but I though you might appreciate the update for reviewing.

Cheers.
Bob.