Fix issue preventing printing on some platforms

Linux printing for some systems blanked the printouts when the gal
screensize was set here.  Restoring the screensize after clearing
ensures that the view redraw is properly scaled

Fixes https://gitlab.com/kicad/code/kicad/issues/19807

common/board_printout.cpp

@@ -175,8 +175,14 @@ void BOARD_PRINTOUT::DrawPage( const wxString& aLayerName, int aPageNum, int aPa
     gal->SetLookAtPoint( drawingAreaBBox.Centre() );
     gal->SetZoomFactor( m_settings.m_scale );
     gal->SetClearColor( dstSettings->GetBackgroundColor() );
+
+    // Clearing the screen for the background color needs the screen set to the page size
+    // in pixels.  This can ?somehow? prevent some but not all foreground elements from being printed
+    // TODO: figure out what's going on here and fix printing.  See also sch_printout
+    VECTOR2I size = gal->GetScreenPixelSize();
     gal->ResizeScreen( pageSizePx.GetWidth(),pageSizePx.GetHeight() );
     gal->ClearScreen();
+    gal->ResizeScreen( size.x, size.y );
 
     if( m_gerbviewPrint )
         // Mandatory in Gerbview to use the same order for printing as for screen redraw

eeschema/printing/sch_printout.cpp

@@ -429,8 +429,14 @@ bool SCH_PRINTOUT::PrintPage( SCH_SCREEN* aScreen, wxDC* aDC, bool aForPrinting
         gal->SetLookAtPoint( drawingAreaBBox.Centre() );
         gal->SetZoomFactor( print_scale );
         gal->SetClearColor( dstSettings->GetBackgroundColor() );
+
+    // Clearing the screen for the background color needs the screen set to the page size
+    // in pixels.  This can ?somehow? prevent some but not all foreground elements from being printed
+    // TODO: figure out what's going on here and fix printing.  See also board_printout
+        VECTOR2I size = gal->GetScreenPixelSize();
         gal->ResizeScreen( pageSizePix.GetWidth(),pageSizePix.GetHeight() );
         gal->ClearScreen();
+        gal->ResizeScreen( size.x, size.y );
 
         // Needed to use the same order for printing as for screen redraw
         view->UseDrawPriority( true );