I have issues running this code with Qt 5.5 (both old and completely fresh install). It works with Qt 5.4 installation (QtPositioning 5.4 used in that case)

import QtPositioning 5.5
import QtQuick 2.0

Rectangle {
    id: root

    PositionSource {
        id: positionSource
    }
}

This is the error:

09:52 PMoan@work7:~/temp$ qmlscene lala.qml
file:///home/oan/temp/lala.qml:1 plugin cannot be loaded for module "QtPositioning": Cannot load library /opt/Qt/5.5/gcc_64/qml/QtPositioning/libdeclarative_positioning.so: (/opt/Qt/5.5/gcc_64/qml/QtPositioning/libdeclarative_positioning.so: undefined symbol: _Z25geoCoordinateInterpolatorRK14QGeoCoordinateS1_d)

Some additional info:

09:54 PMoan@work7:~/temp$ c++filt _Z25geoCoordinateInterpolatorRK14QGeoCoordinateS1_d
geoCoordinateInterpolator(QGeoCoordinate const&, QGeoCoordinate const&, double)

09:58 PMoan@work7:/opt/Qt/5.5/gcc_64$ readelf -Ws lib/libQt5Positioning.so.5.5.1 |grep _Z25geoCoordinateInterpolatorRK14QGeoCoordinateS1_d
514: 000000000002e6b0 642 FUNC GLOBAL DEFAULT 11 _Z25geoCoordinateInterpolatorRK14QGeoCoordinateS1_d

Edit:
Additionally, this is on ubuntu 15.04.