phog: fix hardcoded paths

hosts/modules/gui/sxmo/default.nix

@@ -349,7 +349,16 @@ in
         services.greetd = {
           enable = true;
           settings.default_session.command = "${pkgs.phog}/bin/phog";
+          # this would be nice for debugging, but greetd swallows the logs:
+          # settings.default_session.command =
+          # let
+          #   launch-phog = pkgs.writeShellScriptBin "launch-phog" ''
+          #     echo "launching phog..."
+          #     G_MESSAGES_DEBUG=all ${pkgs.phog}/bin/phog
+          #   '';
+          # in "${launch-phog}/bin/launch-phog" ;
         };
+        environment.pathsToLink = [ "/share/wayland-sessions" ];
       })
 
       # old, greeterless options:

overlays/cross.nix

@@ -1339,6 +1339,9 @@ in {
     # '';
     postPatch = (upstream.postPatch or "") + ''
       sed -i /phog_plugins_dir/d build-aux/post_install.py
+      substituteInPlace src/greetd.c \
+        --replace '/usr/share/wayland-sessions' '/run/current-system/sw/share/wayland-sessions/' \
+        --replace '/usr/share/xsessions' '/run/current-system/sw/share/xsessions'
     '';
     preFixup = (upstream.preFixup or "") + ''
       gappsWrapperArgs+=(