This fixes an issue where an improperly set XDG_DATA_DIRS environment variable would cause a segfault when opening the 'Save As' menu of Inkscape. See: <https://lists.gnu.org/archive/html/help-guix/2020-06/msg00093.html>. * gnu/packages/inkscape.scm (inkscape-1.0)[arguments]: Import the (guix build glib-or-gtk-build-system) module. [phases]: Add the glib-or-gtk-compile-schemas and glib-or-gtk-wrap phases. Reported-by: Thorsten Wilms <t_w_@freenet.de>