GitLab

Takes a member (function) pointer and a value and returns a functor,
that takes a instance of the mfp's class and returns whether it's equal
to value. Sounds complicated, but is a common pattern that is easy to
understand.

Change-Id: Iaaeb90488d34ddfd6940dadd4c66705381198fee
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>