@carousel-control-font-size is ignored on larger screens

Created by: pehlert

Apparently the @carousel-control-font-size setting is ignored on larger screens by hard-coding it to 30px here: https://github.com/twbs/bootstrap/blob/master/less/carousel.less#L243

Can someone point out whether this has been a deliberate decision and if so, what the reason behind it was? Otherwise I'll submit a pull request later which fixes this issue.

Cheers,

Pascal