[metapost] mpsproof fails in TeXLive 2023.

[Karl Berry]

Hi Daniel,

    in mpsproof.tex needs to be replaced with
       \input supp-pdf.mkii

Thanks for the report. I committed the change to mpsproof.tex in TL.
(Luigi, please do it in your upstream, too.)

We could also reintroduce the trivial supp-pdf.tex, but until we get
other bug reports, I guess the path of least resistance is to skip that.

    Also, because supp-pdf.mkii is provided by context

For exactly the reasons you give, many years ago I split supp-pdf.mkii
and related from context to its own TL package, namely mptopdf. It's
included in the core collection-latex, which seems to suffice in
practice; I don't recall getting any related bug reports, anyway.

    context license permits this.

Last I knew, the context license was the GPL (which certainly does
permit such splitting). I admit I haven't looked recently. --thanks, karl.