uiList: fix another bug, where active item labels in sublayouts would not get colored as active (need recursion in sublayouts!). Was affecting e.g. Group node inputs/outputs lists.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61215 954f8c5b-7b00-dc11-b283-0030488c597c