ofz#3834 Divide-by-zero

Change-Id: I654152b964c6228efeb8b7cc7203064338fd1dd6
Reviewed-on: https://gerrit.libreoffice.org/43934
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

filter/source/graphicfilter/icgm/cgm.cxx

@@ -404,6 +404,12 @@ void CGM::ImplSetMapMode()
     else
         mbAngReverse = false;
 
+    if (mnVDCdy == 0.0 || mnOutdy == 0.0)
+    {
+        mbStatus = false;
+        return;
+    }
+
     double fQuo1 = mnVDCdx / mnVDCdy;
     double fQuo2 = mnOutdx / mnOutdy;
     if ( fQuo2 < fQuo1 )