libstore: disable resolve-system-dependencies hook

This is used to determine the dependency tree of impure libraries so nix
knows what paths to open in the sandbox.  With the less restrictive
defaults it isn't needed anymore.

src/libstore/globals.hh

@@ -311,12 +311,7 @@ public:
     Setting<bool> printMissing{this, true, "print-missing",
         "Whether to print what paths need to be built or downloaded."};
 
-    Setting<std::string> preBuildHook{this,
-#if __APPLE__
-        nixLibexecDir + "/nix/resolve-system-dependencies",
-#else
-        "",
-#endif
+    Setting<std::string> preBuildHook{this, "",
         "pre-build-hook",
         "A program to run just before a build to set derivation-specific build settings."};