tests/sw_sync: Add subtest test_alloc_merge_fence

This subtest verifies that merging two fences works in the simples possible
case.

Signed-off-by: Robert Foss <robert.foss@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
1 file changed