I'm indeed responsible for this myself, because I had enable xdm Authentication:
bash-3.2$ grep -n XdmcpWrap ../../os/*
../../os/xdmauth.c:92: XdmcpWrap (&rho, &privateKey,
outgoingData->data, 8);
Now I remember that I got the same error when I rebuilt kdm a month
ago (which is directly derived from xdm, in contrast to gdm which is a
complete [rather buggy and slow] rewrite).
This error comes into existance because libXdmcp.so.6 does not export
the two symbols XdmcpWrap and XdmcpUnwrap anymore, for some time now:
bash-3.2$ nm /usr/X11/lib/libXdmcp.so.6|egrep -e XdmcpWrap -e XdmcpUnwrap|wc -l
0
bash-3.2$
So I apologize for the confusion.
--
%martin