Bug#967565: [Pkg-electronics-devel] Bug#967565: lepton-eda: depends on deprecated GTK 2

[Bastian Germann]

With both autotools and meson buildsystems, the gtksheet-4.0/gtksheet include 
path is intentional.
Mageia is the only other Linux system that I found a gtksheet package on
and they also install the files as intended by the build system, so we should 
rather not deviate.