cogl-path: Undeprecate framebuffer functions

It looks like deprecating the functions with explicit framebuffer/pipeline arguments made it to (cogl) master by mistake:

https://mail.gnome.org/archives/clutter-list/2016-April/msg00008.html

We now use one of them, so this is a good time to undeprecate the lot.

Follow-up from !595 (merged)