[evince] small bug fix for Evince

[Net <akin grad icmc usp br>]

Hello Evince team,

My name is Alexandre, I'm a member of Lab Macambira, a new free software development group in Brazil.
Although we just started, we are interested in helping Evince. 
Please, take a loot at this: https://bugzilla.gnome.org/show_bug.cgi?id=648115.

I fixed a bug and would like to know if I should send the fix to you through Git or
if the above patch is enough. Perhaps Git would be a good idea since I plan to develop evince features
with my dev team. We are thinking about helping with pdf form filling, among others.

Thanks for your efforts!

Alexandre Koji Imai Negrão