Port code from the KWSys System_Shell APIs into cmOutputConverter.
Drop it from our copy of KWSys because upstream will drop it too,
and by doing it in this commit 'git blame' may have an easier time
connecting the history of the content.
The Convert methods never belonged to the local generator concept, so
split them out now. The cmOutputConverter is cheap to construct and
destroy, so it can be instantiated where needed to perform
conversions. This will allow further decoupling of cmLocalGenerator
from the configure step.
Inherit cmLocalGenerator from cmOutputConverter for the purpose of
source compatibility.
Stephen Kelly
Brad King