gnome.gnome-system-monitor: Fix privileged operations

It was checking /usr/bin/pkexec, which is not available on NixOS. Instead, we need to look for the setuid wrapper in /run/wrappers/bin/pkexec.

pkgs/desktops/gnome/core/gnome-system-monitor/default.nix

@@ -30,6 +30,11 @@ stdenv.mkDerivation rec {
     sha256 = "EyOdIgMiAaIr0pgzxXW2hIFnANLeFooVMCI1d8XAddw=";
   };
 
+  patches = [
+    # Fix pkexec detection on NixOS.
+    ./fix-paths.patch
+  ];
+
   nativeBuildInputs = [
     pkg-config
     gettext

pkgs/desktops/gnome/core/gnome-system-monitor/fix-paths.patch

@@ -0,0 +1,13 @@
+diff --git a/src/gsm_pkexec.cpp b/src/gsm_pkexec.cpp
+index 868969ba..51eb93b5 100644
+--- a/src/gsm_pkexec.cpp
++++ b/src/gsm_pkexec.cpp
+@@ -33,6 +33,7 @@ gboolean gsm_pkexec_create_root_password_dialog(const char *command)
+ gboolean
+ procman_has_pkexec(void)
+ {
+-    return g_file_test("/usr/bin/pkexec", G_FILE_TEST_EXISTS);
++    return g_file_test("/run/wrappers/bin/pkexec", G_FILE_TEST_EXISTS)
++        || g_file_test("/usr/bin/pkexec", G_FILE_TEST_EXISTS);
+ }
+