fdo#64632 If a Symbol font is missing, ensure that conversion is done

ImplDevFontList::ImplFindByFont() will nearly always return a font, so
we do not go through the code path which sets up conversion.

Change-Id: Ice361f183c9f42aa562d4caab1d589417ad3fc9a
Reviewed-on: https://gerrit.libreoffice.org/4037Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

vcl/source/gdi/outdev3.cxx

@@ -2309,6 +2309,13 @@ ImplFontEntry* ImplFontCache::GetFontEntry( ImplDevFontList* pFontList,
         maFontInstanceList[ aFontSelData ] = pEntry;
     }
 
+    // We might have selected a non-symbol font as a fallback for a
+    // symbol font. Ensure that conversion is done
+    if (aFontSelData.IsSymbolFont() && !pEntry->maMetric.IsSymbolFont() && !pEntry->mpConversion)
+    {
+        pEntry->mpConversion = ConvertChar::GetRecodeData( aFontSelData.maTargetName, aFontSelData.maSearchName );
+    }
+
     mpFirstEntry = pEntry;
     return pEntry;
 }