bug#26215: gschemas.compiled should not be added to the profile by multiple packages

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

Hello Leo!  Thank you for going through old issues!

So the issue appears to be fixed by commit
de136f3ee7878dea139e751b7e4ca04c2542c91d (from year 2018) making sure
a gschemas.compiled encompassing all packages in a Guix profile gets
created.  Reverting that commit does not print warnings today (I don’t
know why), but still causes choosing one of the packages’
gschemas.compiled over the other.

For normal usage, creating individual, per-package gschemas.compiled
files in glib-or-gtk-build-system probably is *useless*.  Checking the
utility is hard though because I have not found a package that does
not create a per-package gschemas.compiled in their build phase
anyway.

I think the bug is done.  Purging the gschemas.compiled files from all
packages would need to be done in an extra phase for many build
systems (glib-or-gtk build system, cmake build system, meson build
system) that would be useless when a package does not use glib.  It is
difficult.  Also the gschemas.compiled files are small in size.  Some
people maybe even do or could rely on the per-package
gschemas.compiled file in self-written setups that do not use Guix
profiles/environments.

Closing.

Regards,
Florian