gpu_group.c: compute_accessed_by_single_thread_depth: plug leak on error path
gpu_group.c: compute_accessed_by_single_thread_depth: plug leak on error path

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/ppcg,Meinersbur/ppcg