plug-ins: minor follow-up to the icon include fix two commits below

4 jobs for master in 20 minutes and 45 seconds (queued for 1 second)
Status Job ID Name Coverage
  Mypaint Brushes
passed #401308
mypaint-brushes-git

00:01:59

 
  Babl
passed #401309
babl-git

00:02:46

 
  Gegl
passed #401310
gegl-git

00:06:35

 
  Gimp
passed #401311
build-git-autotools

00:09:23