Freeze break for GTK+

[Matthias Clasen <matthias clasen gmail com>]

Ray and I spent several hours today debugging crashes of random
applications when the on-screen keyboard is toggled.
In the end it turned out to be a problem with gtks module loading code
where we added some code to blacklist gail, and got it wrong.

https://bugzilla.gnome.org/show_bug.cgi?id=659966

The patch has been tested by both Ray and me, and it makes toggling
the on-screen keyboard work reliably where before it would crash after
one or two cycles.
There may still be a different a11y-related blocker where the login
screen sometimes freezes after hitting enter in the password entry.