[bug#44700] services: setuid: More configurable setuid support.

[Ludovic Courtès]

Howdy Christine & all!

I’ve just pushed minor tweaks to ‘setuid-programs’ deprecation handling:

  8b9a5641bc system: install, hurd: Use 'setuid-programs'.
  2826f488e4 system: Accept gexps in 'setuid-programs'.
  e0bd47b4fd system: Handle 'setuid-programs' deprecation handling as a field 
sanitizer.
  5291fd7a42 records: Support field sanitizers.

This uses the “field sanitizers” that landed in core-updates a few weeks
ago, and it allows us to emit only one warning per ‘setuid-programs’
field, with source location info:

  gnu/system/hurd.scm:105:2: warning: representing setuid programs with 
file-like objects is deprecated; use 'setuid-program' instead

Let me know if anything’s amiss!

Ludo’.