Fix QGst::Query compilation with msvc.
Fix QGst::Query compilation with msvc.

shadeslayer/qtgstreamer,detrout/qt-gstreamer,nasserGanjali/QtGStreamer,cyndis/qtgstreamer,ylatuya/qt-gstreamer,GStreamer/qt-gstreamer,iperry/qt-gstreamer,knuesel/qt-gstreamer,comicfans/libqtgstreamer,GStreamer/qt-gstreamer,nasserGanjali/QtGStreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer,tswindell/qt-gstreamer,shadeslayer/qtgstreamer,dejunk/gstreamer,cyndis/qtgstreamer,iperry/qt-gstreamer,dejunk/gstreamer,iperry/qt-gstreamer,GStreamer/qt-gstreamer,detrout/qt-gstreamer,dejunk/gstreamer,knuesel/qt-gstreamer,tswindell/qt-gstreamer,comicfans/libqtgstreamer,detrout/qt-gstreamer,ylatuya/qt-gstreamer,tswindell/qt-gstreamer,freedesktop-unofficial-mirror/gstreamer__qt-gstreamer,cyndis/qtgstreamer,ylatuya/qt-gstreamer,nasserGanjali/QtGStreamer,shadeslayer/qtgstreamer,comicfans/libqtgstreamer,knuesel/qt-gstreamer