bug#34759: Gimp plugins not picked up by default

[Jack Hill]

Hi Guix,

I've installed gimp and gimp-resynthesizer into my profile. However, gimp 
does not know about resynthesizer. If I symlink 
~/.config/GIMP/2.10/plug-ins to ~/.guix-profile/lib/gimp/2.0/plug-ins, 
then resynthesizer is found and works correctly. Presumably, our gimp 
package should look in the profile for plugins by default, but it is not 
clear how to do that.

Also, for me, starting gimp with GIMP2_PLUGINDIR set did not help gimp 
find resynthesizer. Even it that did work, it is not clear that we'd want 
that since it is a single directory and not a path.

My guix describe info is as follows:

  guix-at-duke d8c119f
    repository URL: https://gitlab.oit.duke.edu/jackhill/guix-at-duke.git
    branch: master
    commit: d8c119f1d9256484b3106cec700361e7d2f6a15a
  guix c268c6a
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: c268c6a03e5c6f16f06c1ebf0de71a6996d1daf9

Best,
Jack