Some globals are static and it doesn't make sense to destroy them before
the wl_display. For instance, wl_compositor should be created before the
display is started and shouldn't be destroyed.
For these globals, we can simplify the code by removing the destructor
and stop keeping track of wl_resources (these will be destroyed with the
wl_display by libwayland).
It's added to manager->input_methods list in manager_get_input_method, but
wasn't removed anywhere, leading to possible use-after-free in
wlr_input_method_manager_v2_destroy.