vcl: fdo#87510 regression in GetFontMetric

Unfortunately when I refactored the code some time ago in commit 588bb542
I forgot to remove the original assignment to mnExtLeading. This fixes this issue.

Change-Id: I9ef514c1a28ec72747fed865a47c41a1193ce1b9
Reviewed-on: https://gerrit.libreoffice.org/13627Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>

vcl/source/outdev/font.cxx

@@ -197,7 +197,6 @@ FontMetric OutputDevice::GetFontMetric() const
     aMetric.mpImplMetric->mnDescent     = ImplDevicePixelToLogicHeight( pMetric->mnDescent+mnEmphasisDescent );
     aMetric.mpImplMetric->mnIntLeading  = ImplDevicePixelToLogicHeight( pMetric->mnIntLeading+mnEmphasisAscent );
     aMetric.mpImplMetric->mnExtLeading  = ImplDevicePixelToLogicHeight( GetFontExtLeading() );
-    aMetric.mpImplMetric->mnExtLeading  = ImplDevicePixelToLogicHeight( pMetric->mnExtLeading );
     aMetric.mpImplMetric->mnLineHeight  = ImplDevicePixelToLogicHeight( pMetric->mnAscent+pMetric->mnDescent+mnEmphasisAscent+mnEmphasisDescent );
     aMetric.mpImplMetric->mnSlant       = ImplDevicePixelToLogicHeight( pMetric->mnSlant );