[metapost] Fix formatting glitches.

[Andreas Scherer]

Am 20.05.24 um 19:42 schrieb Andreas Scherer:
> Done for TeX Live 2025! (Or rather knuth-{pdf,hint} version 2.3, 
> possibly later this year. I think I'll amend a few TOC pages first.)

After the intermediate project to establish '/PageLabels' in PDF output 
from WEB amd CWEB, I've now revamped project 'MetaPost in knuth-pdf': 
https://github.com/ascherer/mplibdir still starts from TeX Live revision 
71300 with all thirteen CWEB modules and adds change files for at least 
some of them.

* MP.CH applies final (?!) spit and polish to MP.W
* MPOST.CH updates the driver module MPOST.W
* TFMIN.CH and MPSTRINGS.CH play with the two smallest modules

I'm not quite sure if I'll include all 13 modules in knuth-pdf. 
Especially the four *out.w modules look very rough.

Regards,
Andreas