Print qCDebugs in arbitrary categories by default

The debug output of all categories will be visible by default,
except from the "qt.*" categories. "qt.*" categories are private
and their default debug output will be hidden.

[ChangeLog][QtCore][Logging] Enable qCDebug's for all categories except qt one's

Change-Id: Ibe147c8bbe0835a63b3de782288b9c3251321d8f
Reviewed-by: Kai Koehne <kai.koehne@digia.com>