Generate more specific names for unknown members than just "Unknown"

Include the numeric member id in the name. Hopefully makes it a bit
easier to interpret log files produced by LibreOffice or by the COLEAT
tool.

Change-Id: I7270b9538cf1a75db8972fb91eb57b931fe8e320
Reviewed-on: https://gerrit.libreoffice.org/68859
Tested-by: Jenkins
Reviewed-by: Tor Lillqvist <tml@collabora.com>

extensions/source/ole/unoobjw.cxx

@@ -892,7 +892,7 @@ HRESULT STDMETHODCALLTYPE CXTypeInfo::GetDocumentation(MEMBERID memid,
         }
         else
         {
-            *pBstrName = SysAllocString(L"Unknown");
+            *pBstrName = SysAllocString(o3tl::toW(OUString(OUString("UnknownNameOfMember#") + OUString::number(memid)).getStr()));
         }
     }
     if (pBstrDocString)