tdf#93018 - Copying forms not working anymore

Bug introduced by commit fb14be5f
"create new 'enum class' SotClipboardFormatId to unify types"

Change-Id: I3febb927f658ac27d2b864869775db3b71940a5c
(cherry picked from commit f7d65b04)
Reviewed-on: https://gerrit.libreoffice.org/17536Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sot/source/base/exchange.cxx

@@ -253,16 +253,14 @@ SotClipboardFormatId SotExchange::RegisterFormatName( const OUString& rName )
             return static_cast<SotClipboardFormatId>(i + static_cast<int>(SotClipboardFormatId::USER_END) + 1);
     }
 
-    // nMax ist der neue Platz
     DataFlavor* pNewFlavor = new DataFlavor;
-
     pNewFlavor->MimeType = rName;
     pNewFlavor->HumanPresentableName = rName;
     pNewFlavor->DataType = cppu::UnoType<OUString>::get();
 
     rL.push_back( pNewFlavor );
 
-    return static_cast<SotClipboardFormatId>(static_cast<int>(nMax) + static_cast<int>(SotClipboardFormatId::USER_END) + 1);
+    return static_cast<SotClipboardFormatId>(static_cast<int>(rL.size()-1) + static_cast<int>(SotClipboardFormatId::USER_END) + 1);
 }
 
 SotClipboardFormatId SotExchange::RegisterFormatMimeType( const OUString& rMimeType )