Comment # 2 on bug 97585 from Nicolai Hähnle

This seems to be the crucial message:

libGL: dlopen /usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so failed
(/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so: undefined symbol:
drmFreeDevice)

drmFreeDevice should be provided by libdrm. You can use `ldd
/usr/lib/x86_64-linux-gnu/dri/radeonsi_dri.so` or additional LD_DEBUG flags to
check where libdrm.so comes from. Probably something went wrong while
installing the PPA.