gpsd: add listenany option

nixos/modules/services/misc/gpsd.nix

@@ -77,6 +77,14 @@ in
         '';
       };
 
+      listenany = mkOption {
+        type = types.bool;
+        default = false;
+        description = lib.mdDoc ''
+          Listen on all addresses rather than just loopback.
+        '';
+      };
+
     };
 
   };
@@ -106,6 +114,7 @@ in
             -S "${toString cfg.port}"                             \
             ${optionalString cfg.readonly "-b"}                   \
             ${optionalString cfg.nowait "-n"}                     \
+            ${optionalString cfg.listenany "-G"}                  \
             "${cfg.device}"
         '';
       };