[cairo] Brand new _cairo_lround implementation

[Bill Spitzak]

Daniels code does round-away-from-zero, apparently. I think floor or 
ceil is needed consistently. Otherwise when something crosses zero it 
may offset by 1 pixel. Could this be the problem?

Carl Worth wrote:

> Thanks for the detailed description. I tried that and I did succeed in
> demonstrating a bug that appears in Daniel's patch, but not mine.
> 
> So far I've only seen the bug occur on the second line of a folder
> icon that had a name long enough to break onto two lines.