Request: mute output to .xsession-errors and/or disable backup

[stephematician]

This isn't a bug so much as a feature request.

There are some bugs in other applications where the ~/.xsession-erros log is spammed (e.g. https://bugs.launchpad.net/ubuntu/+source/glib-networking/+bug/2047457). The ideal scenario is that these bugs are fixed and the solution is passed downstream quickly - but this isn't always the case.

A user (with other session managers) might be able to mitigate the problem by symlinking it to /dev/null (e.g. https://askubuntu.com/questions/177058/xsession-errors-file-is-huge-how-can-i-disable); however that's not the case in lightdm because it will move the ~/.xsession-errors file and create a new one (which removes the symlink), as introduced here: 602dcab

It might be helpful to have an option to change the behaviour of the ~/.xsession-errors log backup as with other logs; or to switch off logging (e.g. via a user option).

As it stands, I think it is possible to mitigate the problem another way - chattr +i the log file; but I haven't figured out the consequences of that entirely (i.e. is writing to the file a no-op as desired)?