Which packages to install to get debugging symbols for Xorg server

Sometimes when resuming from suspend, my screen goes black, no input is accepted, and I'm forced to hard reboot. I discovered a core file, so I ran

sudo gdb --core=/core

which output:

Core was generated by `/usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -noliste'.
Program terminated with signal SIGBUS, Bus error.

There was no info in /var/log/Xor.0.log.old, apport generated a crash report under /var/crash but I couldn't decypher any meaningful info from it, /var/log/apport.log had a suspicious entry for the time of the crash:

ERROR: apport (pid 2725) Sat Jun  2 06:11:13 2018: is_closing_session(): no DBUS_SESSION_BUS_ADDRESS in environment

My graphics card uses driver i915 from package xserver-xorg-video-intel, so I installed xserver-xorg-video-intel-dbg to have its debugging symbols. All web pages about X debugging recommended installing xserver-xorg-core-dbg, but this package doesn't exist since Ubuntu 16.04, and I haven't found any equivalent package.

Does anybody know what package to install to get X core debugging symbols ?