Fix some copy/paste errors identified by Coverity

Author: nyalldawson

src/app/qgscustomprojectiondialog.cpp

@@ -498,7 +498,7 @@ void QgsCustomProjectionDialog::on_pbnCalculate_clicked()
                               tr( "Internal Error (source projection invalid?)" ) );
     projectedX->setText( "" );
     projectedY->setText( "" );
-    pj_free( myProj );
+    pj_free( wgs84Proj );
     return;
   }
 

src/core/raster/qgsrasterlayerrenderer.cpp

@@ -68,7 +68,7 @@ QgsRasterLayerRenderer::QgsRasterLayerRenderer( QgsRasterLayer* layer, QgsRender
     catch ( QgsCsException &cs )
     {
       QgsMessageLog::logMessage( QObject::tr( "Could not reproject layer extent: %1" ).arg( cs.what() ), QObject::tr( "Raster" ) );
-      myProjectedViewExtent.setMinimal();
+      myProjectedLayerExtent.setMinimal();
     }
   }
   else

src/providers/postgres/qgspostgresconn.cpp

@@ -782,7 +782,7 @@ QString QgsPostgresConn::postgisVersion()
     QStringList gist = postgisParts.filter( "STATS" );
     if ( gist.size() == 1 )
     {
-      mGistAvailable = ( geos[0].indexOf( "=1" ) > -1 );
+      mGistAvailable = ( gist[0].indexOf( "=1" ) > -1 );
     }
     QStringList proj = postgisParts.filter( "PROJ" );
     if ( proj.size() == 1 )