And reset the grab_location in the ::released handler of the multipress
gesture.

Previously, when leaving fine-tune mode, the ::released handler of the
multipress gesture would call stop_scrolling, which calls
range_grab_remove and resets the grab_location. The ::drag-end handler
is executed after that, and only unsets priv->in_drag if the
grab_location is MOUSE_OUTSIDE, which it never was, since the ::released
handler already reset it. This lead to priv->in_drag being set even
though no dragging was in progress anymore, which e.g. made shift
pressed after leaving the fine-tune mode entering it again.

https://bugzilla.gnome.org/show_bug.cgi?id=761402