top-level: use parentheses to group checks

Group `throwIfNot` chains with parentheses to improve readability and
hint to nixfmt the intended formatting.

This makes the result visually closer to the pre-nixfmt layout:

    checked =
      throwIfNot (lib.isList overlays) "The overlays argument to nixpkgs must be a list."
      lib.foldr (x: throwIfNot (lib.isFunction x) "All overlays passed to nixpkgs must be functions.") (r: r) overlays
      throwIfNot (lib.isList crossOverlays) "The crossOverlays argument to nixpkgs must be a list."
      lib.foldr (x: throwIfNot (lib.isFunction x) "All crossOverlays passed to nixpkgs must be functions.") (r: r) crossOverlays
      ;

0 files changed, 0 insertions, 0 deletions