You can use this to install dependency rather than apt-get the old 5.34
sudo apt-get install git dpkg-dev make g++ gcc binutils libx11-dev libxpm-dev libxft-dev libxext-dev
(stole from this post: Root 6.04 on Ubuntu 15.04)
In my experience from the first fast ring build that have this, it crashed occasionally. The new one 14332 seem to fair better.
This isn’t helpful for me though since I want to code and build native Win32 binary, so I’m still eagerly awaiting Win32 ROOT6. Hopefully sometime soon-ish? 