libxkbui: Fix license WARNING

WARNING: libxkbui-1_1.0.2-r10 do_populate_lic: libxkbui: No generic license file exists for: GPL in any provider

sources have:
Copyright (c) 1996 by Silicon Graphics Computer Systems, Inc.

so picked "SGI-1"

Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
(cherry picked from commit 901b9a2ec805b3be0dfdd9a399c5969c2b580029)
Signed-off-by: Armin Kuster <akuster808@gmail.com>