[patch] Make dbus-launch always (if possible) save session information in X11

[Havoc Pennington]

Hi,

Sjoerd Simons wrote:
> Attached patch makes a normal dbus-launch also save it's session information in
> X11 and not just an autolaunched bus as it is currently.
> 
> This makes DISPLAY=:0 <application> just work as one expects it. See the patch
> for more info.
> 

Thanks, comments:

- remember to do ChangeLog, then paste into the git log (with a one-line
   git-type summary in front)
- are you sure we didn't do this autolaunch-only on purpose?
   it doesn't seem like we'd have done this accidentally.
   it might be worth going through the archived discussion.
- it would be good if Thiago could review this before commit
- this code (before you touched it also) is very, very confusing to me
   for some reason - not sure if it's all the many dbus-launch modes or
   what... ;-)
- you might check whether any dbus-launch man page updates are required,
   and also be sure to test all the scenarios described in the man page

Havoc