MFH: r551328

x11/gdm: Install gconftool-2 as it is needed by pkg-install

Before this patch, the following error could be observed during the
installation of the port:

===> Creating homedir(s)
/bin/sh: gconftool-2: not found
chown: /usr/local/etc/gdm/home/.gconf.mandatory: No such file or directory
chmod: /usr/local/etc/gdm/home/.gconf.mandatory: No such file or directory
chmod: /usr/local/etc/gdm/home/.gconf.mandatory/*.xml: No such file or directory
GDM is installed.

Specifying USE_GNOME+=gconf2 seems to fix the error messages.

(BTW, for some reason the gconf2 dependency was removed in r372768.)

Approved by: portmgr blanket

Approved by: ports-secteam (fluffy)