ConsumeOutput: Use local encoding to parse executable output

We don't really know which encoding the app will use. local 8 bit
seems to be the best bet though.

Change-Id: Ic4d8668ed5f5a6eca55d44348ae54adb903bf447
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>
Reviewed-by: Niels Weber <niels.weber@digia.com>