Try to deinstall textproc/p5-XML-Parser and install Xfce4 only.
Making all in lgpl
/usr/local/bin/xml2po: not found
gmake[3]: *** [ar/lgpl.xml] Error 127
gmake[2]: *** [all-recursive] Error 1
gmake[1]: *** [all-recursive] Error 1
gmake: *** [all] Error 2
*** Error code 1
Stop in /usr/ports/x11/gnome-desktop.
*** Error code 1
Stop in /usr/ports/x11/gdm.
*** Error code 1
Stop in /usr/ports/x11/gdm.
*** Error code 1
Stop in /usr/ports/x11-wm/xfce4.
*** Error code 1
Stop in /usr/ports/x11-wm/xfce4.
#whereis xml2po
xml2po: /usr/local/bin/xml2po /usr/local/man/man1/xml2po.1.gz