With all the three paths this is quite a handful of code, and it was mostly
duplicated in two places. A follow-up patch would need to introduce a third
copy of it. Therefore move the code into a helper function.
There are two behavioral changes:
- The format error now prints the string code as well, because it is easy to
read.
- The g_debug() in init_dumb_fb() is removed. Did not seem useful.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/810
There is no reason why we should have an internal type enum when we have
all the infrastructure to just use multiple GObject types. Also there
was no code sharing between the old "types", the only common API was
getting the framebuffer ID, so lets make that a vfunc.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/584
