treewide: cups_filters -> cups-filters

nixos/modules/services/printing/cupsd.nix

···
 
 let
 
-  inherit (pkgs) cups cups-pk-helper cups_filters gutenprint;
+  inherit (pkgs) cups cups-pk-helper cups-filters gutenprint;
 
   cfg = config.services.printing;
 
···
   bindir = pkgs.buildEnv {
     name = "cups-progs";
     paths =
-      [ cups.out additionalBackends cups_filters pkgs.ghostscript ]
+      [ cups.out additionalBackends cups-filters pkgs.ghostscript ]
       ++ optional cfg.gutenprint gutenprint
       ++ cfg.drivers;
     pathsToLink = [ "/lib/cups" "/share/cups" "/bin" ];
···
 
         path = [ cups ];
 
-        serviceConfig.ExecStart = "${cups_filters}/bin/cups-browsed";
+        serviceConfig.ExecStart = "${cups-filters}/bin/cups-browsed";
 
         restartTriggers = [ browsedFile ];
       };

pkgs/development/libraries/poppler/default.nix

···
 , minimal ? false, suffix ? "glib"
 }:
 
-let # beware: updates often break cups_filters build
+let # beware: updates often break cups-filters build
   version = "0.46.0"; # even major numbers are stable
   sha256 = "11z4d5vrrd0m7w9bfydwabksk273z7z0xf2nwvzf5pk17p8kazcn";
 in