Use the system's DISPLAY env variable for tests.
Use the system's DISPLAY env variable for tests.

On linux the correct value for the $DISPLAY is required to open
the X display to initialize the GL context. On systems, where the
value is not `:0`, the tests currently fail.

google/gapid,Qining/gapid,google/agi,google/agi,Qining/gapid,Qining/gapid,pmuetschard/gapid,pmuetschard/gapid,pmuetschard/gapid,google/gapid,google/agi,google/gapid,Qining/gapid,google/gapid,google/agi,google/agi,pmuetschard/gapid,Qining/gapid,google/gapid,google/gapid,Qining/gapid,Qining/gapid,pmuetschard/gapid,google/agi,google/gapid,google/agi,google/gapid,google/agi,pmuetschard/gapid,pmuetschard/gapid,pmuetschard/gapid,Qining/gapid