[RFC] Getting GnomeKeyring + PAM to work out of the box

[Marcin Wisnicki]

Increasing number of Gnome and third-party applications are using 
GnomeKeyring for their key/password storage needs.

Currently this means that after every login one have to enter key for 
every keyring (usually just 1).
Most linux distributions automate this with a help of pam_keyring module.
This system is well described here: http://live.gnome.org/GnomeKeyring/Pam

Fortunately all necessary ingredients are already present in the system, 
they just need proper configuration.

For this to work in a plug-and-play manner I propose following changes:

1. Move /etc/pam.d/gdm from base system to x11/gdm port
2. Add KEYRING option (enabled by default) to x11/gdm that:
   (1)  Adds runtime dependency on security/gnome-keyring
   (2)  Appends/uncomments pam_keyring lines in pam.d/gdm so it looks like
	this (maybe it makes more sense to just "include system" ?):

=== gdm.in (to be installed as /usr/local/etc/pam.d/gdm) ===
auth     required  pam_unix.so   no_warn try_first_pass
auth     optional  %%LOCALBASE%%/lib/security/pam_gnome_keyring.so

account  required  pam_nologin.so
account  required  pam_unix.so

session  required  pam_permit.so
session  optional  %%LOCALBASE%%/lib/security/pam_gnome_keyring.so  auto_start
=== 8< ===

I can provide patches if gnome@ agrees to the changes.