Log Message:
a2ps: update to 4.15.4.

* Noteworthy changes in release 4.15.4 (2023-04-13) [stable]
 * Bug fixes:
   - Fix to read configured paper size correctly with libpaper 1.x.
 * Documentation:
   - Various minor documentation improvements.
 * Build system:
   - Fix tests when building with libpaper 1.x.
   - Require gperf for bootstrapping, and use it correctly in build system.
   - Require a new-enough version of texinfo.