Bump socket buffer size

[abbradar]

Fix receiving long library paths. This helps on NixOS, where library paths contain hashes.

[amonakov]

Thanks. Can you show how the problematic string looks on NixOS?

[abbradar]

For example:

/nix/store/6pnqm65dssww0qjc0ngfraj9764m0jfq-nvidia-x11-375.26-4.9.6/lib:/nix/store/h9fixrllhyqx7h04kl52cmd8pk1n4ybp-libglvnd-2016-12-22/lib:/nix/store/1cq45g2w4h09mw1ic3m2dwr21pa7a8ci-nvidia-x11-375.26/lib:/nix/store/gbz0y3jjvk4flmiisfr0wym01x1gsqaj-libglvnd-2016-12-22/lib

We have each package placed into a separate directory with a hash to ensure several nice Nix properties. So we have four paths (two per architecture).