Upgrading to roaring 0.4.5 (bug fix release)

I recommend upgrading roaring to 0.4.5 as it fixes a rarely occurring bug in iterators (that would otherwise throw an unwarranted exception). The upgrade should have no other consequence.

Author: Daniel Lemire <lemire@gmail.com>

Closes #3044 from lemire/master and squashes the following commits:

54018c5 [Daniel Lemire] Recommended update to roaring 0.4.5 (bug fix release)
048933e [Daniel Lemire] Merge remote-tracking branch 'upstream/master'
431f3a0 [Daniel Lemire] Recommended bug fix release