I'm working on Gentoo/FreeBSD project and I'm having trouble installing 
xorg-x11 package on our current setup, as enabling pam support makes it 
complain about missing include files and variables, which are Linux-PAM 
specific (Linux-PAM is the default PAM implementation in most linux systems 
and iirc the 4.x series of FreeBSD, instead 5.x which is the base system we 
start from uses OpenPAM http://www.openpam.org/ ) which is a smaller 
implementation. 
 
The patch I'm attaching makes X.Org compile pam support cleanly on my system, 
but I can't say for sure if it works exactly as it should as I'm not able to 
complete its build for another problem. 
 
HTH, 
Diego