fixed output derivations: fix incorrect responses for getpwuid

Passing nscd socket into the build environment causes unexpected behavior in programs that make getpwuid and other related calls.

relevant threads:
- NixOS#4991
- https://discourse.nixos.org/t/haunted-nix-build-breaks-isolation/13869

src/libstore/build/local-derivation-goal.cc

@@ -1754,7 +1754,7 @@ void LocalDerivationGoal::runChild()
                 /* N.B. it is realistic that these paths might not exist. It
                    happens when testing Nix building fixed-output derivations
                    within a pure derivation. */
-                for (auto & path : { "/etc/resolv.conf", "/etc/services", "/etc/hosts", "/var/run/nscd/socket" })
+                for (auto & path : { "/etc/resolv.conf", "/etc/services", "/etc/hosts" })
                     if (pathExists(path))
                         ss.push_back(path);
             }