Rebuild everything

[Alex Merry]

Over the course of the KF5 sprint, we changed a bunch of installation
directories, including those used by KService, KNotifications and
KPluginLoader. As a result, I suggest you do a full rebuild from
extra-cmake-modules upwards. If you only rebuild some stuff, important
files may not be found and/or the configure step may fail.

Sorry this was so late in the cycle.

Alex