[PATCH] exa: only draw valid trapezoids

[Julien Cristau]

On Wed, Oct  2, 2013 at 15:47:54 +0200, Maarten Lankhorst wrote:

> Fixes freedesktop.org bug https://bugs.freedesktop.org/show_bug.cgi?id=67484
> 
> If t->bottom is close to MIN_INT, removing top can wraparound, so do the check properly.

Does the underflow affect users of xTrapezoidValid other than exa?  Also
should we check for valid traps up-front and send an error back instead
of dropping the rendering?

Cheers,
Julien