QGeoMap: handle map items added before a plugin is available
QGeoMap: handle map items added before a plugin is available

Delay calling setMap() on new items if the map plugin is not yet
available, then call this once it is.

Task-number: QTBUG-24740
Change-Id: Ic331b812915f6b2eb4ca4fd3e43078b7a1509501
Reviewed-by: Ian Chen <4647cc84a579898a3b0880227eafb39d49b3bbfd@nokia.com>
Reviewed-by: Alex Wilson <75fe28a89a52dd8f665f8aed10f0a66d41b4f1d0@nokia.com>

amccarthy/qtlocation,amccarthy/qtlocation,kobolabs/qtlocation,kobolabs/qtlocation,kobolabs/qtlocation,amccarthy/qtlocation