Fix crosshair cursor not showing in red eye reduction tool

Summary:
`RedEyeReductionTool::toolActivated` sets `Qt::CrossCursor` to allow for
more precise positioning where to apply the red eye reduction.

Due to `RasterImageView::setCurrentTool` calling `updateCursor`
afterwards, that change is immediately overridden again, though.

By moving around the latter, the issue can be fixed.

BUG: 321933
FIXED-IN: 18.08.0

Test Plan:
In {nav View} mode, activate the {nav Red Eye Reduction} tool. A
crosshair cursor should show, and hide again upon closing the tool.

Reviewers: #gwenview, ngraham

Reviewed By: #gwenview, ngraham

Subscribers: muhlenpfordt, ngraham

Differential Revision: https://phabricator.kde.org/D14386