D28221: Don't write default value to configuration file when default value came from /etc/* file

[Benjamin Port]

bport planned changes to this revision.

REPOSITORY
  R237 KConfig

REVISION DETAIL
  https://phabricator.kde.org/D28221

To: bport, ervin, dfaure, davidedmundson
Cc: kde-frameworks-devel, LeGast00n, cblack, michaelh, ngraham, bruns