coverity#1371150 Missing move assignment operator

Change-Id: Iaf59b0dfc822fd00563ae15d25fde8c3cf2e2462
Reviewed-on: https://gerrit.libreoffice.org/28614Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/vcl/mapmod.hxx

@@ -59,6 +59,7 @@ public:
     double          GetUnitMultiplier() const;
 
     MapMode&        operator=( const MapMode& rMapMode );
+    MapMode&        operator=( MapMode&& rMapMode );
     bool            operator==( const MapMode& rMapMode ) const;
     bool            operator!=( const MapMode& rMapMode ) const
                         { return !(MapMode::operator==( rMapMode )); }

vcl/source/gdi/mapmod.cxx

@@ -181,6 +181,12 @@ MapMode& MapMode::operator=( const MapMode& rMapMode )
     return *this;
 }
 
+MapMode& MapMode::operator=( MapMode&& rMapMode )
+{
+    mpImplMapMode = std::move(rMapMode.mpImplMapMode);
+    return *this;
+}
+
 bool MapMode::operator==( const MapMode& rMapMode ) const
 {
    return mpImplMapMode == rMapMode.mpImplMapMode;