Fix missing switch to "C" locale before plotting board files.

pcbnew/dialogs/dialog_plot.cpp

@@ -1325,6 +1325,7 @@ void DIALOG_PLOT::Plot( wxCommandEvent& event )
         // Save the current plot options in the board
         m_editFrame->SetPlotSettings( m_plotOpts );
 
+        LOCALE_IO dummy;    // Ensure the "C3 locale is used by the plotter
         PCB_PLOTTER pcbPlotter( m_editFrame->GetBoard(), &reporter, m_plotOpts );
 
         LSEQ layersToPlot = m_plotOpts.GetLayerSelection().UIOrder();

pcbnew/pcbnew_jobs_handler.cpp

@@ -916,6 +916,7 @@ int PCBNEW_JOBS_HANDLER::JobExportPdf( JOB* aJob )
             return CLI::EXIT_CODES::ERR_INVALID_OUTPUT_CONFLICT;
         }
 
+        LOCALE_IO dummy;
         if( !pcbPlotter.Plot( aPdfJob->GetFullOutputPath(), aPdfJob->m_printMaskLayer,
                               aPdfJob->m_printMaskLayersToIncludeOnAllLayers, false ) )
         {