imagemagick: use libjxl on aarch64-linux, as it builds now for that target
imagemagick: use libjxl on aarch64-linux, as it builds now for that target

Works since f24cab5396085e138ff82d53888af8a9a7d83055

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs