This commit is separate from the previous to make it immediately clear (by
comparing files) that the previous commit is a simple move with no modification
whatsoever of the icons/ directory, i.e. the symmetrical removal of add commit
gimp-data@8b54490.
We now clone gimp-data as a meson subproject. I am currently testing the
subproject feature though I am doubting a bit because of its limitations: the
git clone is not updated automatically, nor are errors clear. Therefore it would
be easy to end up with outdated data for developers not manually and regularly
running:
> meson subprojects update
Worse, it looks like even when updating the suproject, it fails to be properly
reconfigured. See: https://github.com/mesonbuild/meson/issues/12898
686897e35d