* gnu/packages/package-management.scm (flatpak): Substitute a marker in
icon-validator/validate-icon.c for the store location.
* gnu/packages/patches/flatpak-fix-icon-validation.patch: Bind the guix
store during flatpak-validate-icon invocation in sandbox mode, along
with a few environment variables necessary for image format detection.
Change-Id: I15dfdd0ecadc57ed383e2985c1c3caa36be4a1de
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
