gpu.c: group_array_references: return -1 on error rather than aborting
gpu.c: group_array_references: return -1 on error rather than aborting

Signed-off-by: Sven Verdoolaege <e5350bbed4977f5eb8ae1dc6abd9ae59d21ace75@kotnet.org>

Meinersbur/ppcg,nicolasvasilache/ppcg,Meinersbur/ppcg,nicolasvasilache/ppcg