eclass/xdg: upgrade for EAPI 7

BUG=chromium:1099508
TEST=build

Change-Id: I40b8e5b12547730baf8ec53349e6c5b26dda9700
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2268632
Tested-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Allen Webb <allenwebb@google.com>
Commit-Queue: Brian Norris <briannorris@chromium.org>
1 file changed