[bug#27657] [PATCH] gnu: graphviz: Update to 2.40.1.

[Arun Isaac]

> With 970 dependents, this should go to a new ‘staging’ branch to be
> merged after ‘core-updates’ is merged.  Fine with you?

I've made the changes suggested by Marius Bakke and pushed to a new
staging branch.

However, there is more about the graphviz package:

Several of the inputs don't seem to be required. graphviz builds
successfully and without any change of features (as reported by the
configure phase) when built without those inputs.

Also, I think the swig input should actually be a native input.

I'll shortly send a patch with these changes. Do review and offer
feedback.

Thanks.