Revert "Get rid of KDELibs4Support"

It breaks the settings pages for suspend (the page opens and by the time
it wants to populate the combo boxes the DBus reply hasn't arrived yet) and
potentially also the profile generator (ie. you probably won't get suspend
by default on a fresh setup...)

Don't get me wrong, this patch is fine, it's just those two little things that
need to be addressed but weren't and the 5.10 release is closing... :/

This reverts commit cdd1a63d.