killing kde4workspace usage in oxygen

Wed Aug 19 10:51:03 UTC 2015

Heya,

oxygen 5.4 and master complain about

> -- Could NOT find KDE4Workspace (missing:  KDE4Workspace_CONFIG) (Required is at least version "4.9.80")

it is apparently only used to build the legacy-kwin decoration.

Seeing as kde-workspace LTS is expiring this month (i.e. no further
support) I think we should kill its usage in oxygen for Plasma 5.4 and
onwards.

HS