Fix the dependency by making the stamp an actual (yet empty/no-op)
header file which is included by all generated source file. This way, we
ensure that meson rebuild .o files when the .pdb sources are changed.
This is the second solution proposed by eli-schwartz here:
https://github.com/mesonbuild/meson/issues/10196#issuecomment-1080053413
Add new PDB group "drawable_edit" which has all procedures from the
"edit" group which are not cut/copy/paste.
The new group's procedures don't have opacity, paint_mode
etc. arguments but take them from the context instead. Unlike the old
gimp-edit-fill, gimp-drawable-edit-fill now uses the context's opacity
and paint_mode.
The new gimp-drawable-edit-gradient-fill procedure uses even more
context properties which are also newly added with this commit
(gradient_color_space, gradient_repeat_mode, gradient_reverse).
And some cleanup in context.pdb.
This is still WIP, nothing in the edit group is depcreated yet.
The enums have to be menually registered in pdb/enums-external.pl.
Currently supports enums from GEGL only.
Add enum GeglDistanceMetric as first external enum.
It never belonged inside "tools". Also rename its "pdb" subdirectory
to "groups". This had to happen before 2.10 so cherry-picking between
branches doesn't become a nightmare in the future.