[perl #112678] [BUG] 'div' for Ints truncates towards 0 when it should round down in Rakudo

[Christian Bartolomaeus via RT]

This works now:

$ perl6-m -e 'say (-8) div 3'
-3

I added a test to S03-operators/div.t with the following commit: 
https://github.com/perl6/roast/commit/d03302f512