Bug#1099646: transition: gnat

[Nicolas Boulenguez <nicolas@debian.org>]

> It might be because e.g. the gprbuild binary package has a dependency
> on libgnatprj12.
> I am open to trying suggestions for improving the ben file.

Apparently
.source ~ /gcc/ in is_affected
  intends to match gcc-11 gcc-12 gcc-13 gcc-14-cross-ports and so on.
.depends ~ /libgnat/ in is_bad
  is always true because is_affected already applies the same filter.
.depends ~ /libgnat-14/ in is_good and is_bad
  intends to select only libgnat-14.
so I suggest this.

is_affected =   .depends ~ /^libgnat-/ & !.source ~ /^gcc-/
is_good     =   .depends ~  "libgnat-14"
is_bad      = ! .depends ~  "libgnat-14"