Ignore cairo errors when SavedCr is dropped
Ignore cairo errors when SavedCr is dropped

Drop cannot fail, unfortunately.  I think we can work towards removing
SavedCr within drawing_ctx.rs because now all the Cairo work is being
done there, and may be able to just mutate the context without
restoring it all the time.

Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/516>

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg