In TranslationUnit, the "normal" lines are based on utf16char offsets,
but the preprocessor lines were based on byte/latin1 offsets.
The preprocessor lines are now based on utf16char offsets, too.
Task-number: QTCREATORBUG-7356
Change-Id: I3c41d1dcee8e9e487210f36da806b0229d3f4cd0
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>