Any application using libGL will report the following errors to stderr:
libGL error: Version 4 or later of flush extension not found
libGL error: failed to load driver: i915
The reason is that the i915 driver does not support DRI3 (yet?)
as per upstream bug report:
https://www.libreoffice.org/bugzilla/show_bug.cgi?id=81601
See also:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=754297
(Ealier version of this bug, which caused crashes)
The best fix would of course be to add version 4 flush extension to the i915 driver.
But if this isn't easily possible, there should be some flag indicating that this driver
is not DRI3 compatible, and DRI3 should then be disabled without an error (that
sounds as if OpenGL does not work at all).
Maybe DRI3 is only supported for 2D on this graphics board? After all the log reports:
But the mesa libGL will fail at DRI3.
Setting "LIBGL_DRI3_DISABLE=1" makes the error message disappear.