[xfce] Add back the extended package group
[xfce] Add back the extended package group

Build blockers have been eliminated.

gumstix/meta-gumstix-extras,gumstix/meta-gumstix-extras,allsey87/meta-bebot-temp,allsey87/meta-bebot-temp,allsey87/meta-bebot-temp,gumstix/meta-gumstix-extras