Export to PNG: also Calc has MeasureUnit

Though meFieldUnit appears to not be used anywhere, but ...

Change-Id: I99e8392e4a773ba00868904e0f2ff5fdbc4bc47d
Reviewed-on: https://gerrit.libreoffice.org/40521Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

filter/source/graphic/GraphicExportDialog.cxx

@@ -130,6 +130,10 @@ void GraphicExportDialog::setSourceDocument( const Reference<XComponent>& xDocum
         {
             aConfigPath = "Office.Draw/Layout/Other/MeasureUnit";
         }
+        else if ( xServiceInfo->supportsService("com.sun.star.sheet.SpreadsheetDocument") )
+        {
+            aConfigPath = "Office.Calc/Layout/Other/MeasureUnit";
+        }
         else if ( xServiceInfo->supportsService("com.sun.star.text.TextDocument") || xServiceInfo->supportsService("com.sun.star.text.WebDocument") )
         {
             aConfigPath = "Office.Writer/Layout/Other/MeasureUnit";