rely on forward declare of boost::optional

Change-Id: Ic3718290944b813b5ac2712fd4006dc97f5b68a0
Reviewed-on: https://gerrit.libreoffice.org/59613
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/filter/msfilter/svdfppt.hxx

@@ -45,7 +45,6 @@
 #include <tools/solar.h>
 #include <vcl/graph.hxx>
 #include <salhelper/simplereferenceobject.hxx>
-#include <boost/optional.hpp>
 
 namespace boost {
     template <class T> class optional;