Missing loadable libraries when running pg_upgrade 9.1 -> 9.2

using Windows XP SP3 (32bit).

When running pg_upgrade with the --check option I get the following error:

Your installation references loadable libraries that are missing from the
new installation. You can add these libraries to the new installation,
or remove the functions using them from the old installation. A list of
problem libraries is in the file:
loadable_libraries.txt

The content of loadable_libraries.txt is:

Could not load library "$libdir/targetinfo"
ERROR: could not access file "$libdir/targetinfo": No such file or directory

Could not load library "$libdir/plugins/plugin_debugger"
ERROR: could not access file "$libdir/plugins/plugin_debugger": No such file or directory

And indeed there is no targetinfo.dll and no plugin_debugger.dll for 9.2 (there isn't even a plugins directory in lib)

The relevant entries in the postgresql.conf for 9.1 are this:

#shared_preload_libraries = '' # (change requires restart)
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''

So I'm a bit stumped on why pg_upgrade thinks that I'm using those libraries. Is there a way to find out which function (or extension?) is using those libraries in order to remove that dependency?

The alternative would be to install those libraries, but the StackBuilder doesn't list them, and I didn't find anything in pgAdmin that would allow me to install them. They weren't installed with the installer and they are not part of the Windows ZIP distribution either.

Any ideas?

Thanks in advance
Thomas