[gnome-shell] shell/app: Fix small memory leak in get_pids()

[Marge Bot <marge-bot src gnome org>]

commit fb75120a392b846153d4eb9d6d3fde96a6d7b602
Author: Sebastian Keller <skeller gnome org>
Date:   Wed Jul 6 19:34:23 2022 +0200

    shell/app: Fix small memory leak in get_pids()
    
    The iterator was pointing to NULL when going out of scope, leading to
    autofree not clearing the list.
    
    ==300183== 32 bytes in 2 blocks are definitely lost in loss record 14,798 of 38,939
    ==300183==    at 0x484586F: malloc (vg_replace_malloc.c:381)
    ==300183==    by 0x4D7D980: g_malloc (gmem.c:127)
    ==300183==    by 0x4D95AB3: g_slice_alloc (gslice.c:1074)
    ==300183==    by 0x4D96D96: g_slist_prepend (gslist.c:282)
    ==300183==    by 0x487854F: shell_app_get_windows (shell-app.c:794)
    ==300183==    by 0x48791A1: shell_app_get_pids (shell-app.c:1201)
    ==300183==    by 0x488B293: shell_window_tracker_get_app_from_pid (shell-window-tracker.c:702)
    ==300183==    by 0x488B632: get_app_from_window_pid (shell-window-tracker.c:370)
    ==300183==    by 0x488B632: get_app_for_window (shell-window-tracker.c:436)
    ==300183==    by 0x488B632: track_window (shell-window-tracker.c:549)
    ==300183==    by 0x4CDBB75: g_cclosure_marshal_VOID__OBJECTv (gmarshal.c:1910)
    ==300183==    by 0x4CD8BE9: _g_closure_invoke_va (gclosure.c:893)
    ==300183==    by 0x4CF2A28: g_signal_emit_valist (gsignal.c:3406)
    ==300183==    by 0x4CF2C2C: g_signal_emit (gsignal.c:3553)
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2367>

 src/shell-app.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/src/shell-app.c b/src/shell-app.c
index 96fe31bff3..5c38a9c8d8 100644
--- a/src/shell-app.c
+++ b/src/shell-app.c
@@ -1195,10 +1195,12 @@ GSList *
 shell_app_get_pids (ShellApp *app)
 {
   GSList *result;
-  g_autoptr (GSList) iter = NULL;
+  g_autoptr (GSList) windows = NULL;
+  GSList *iter;
 
   result = NULL;
-  for (iter = shell_app_get_windows (app); iter; iter = iter->next)
+  windows = shell_app_get_windows (app);
+  for (iter = windows; iter; iter = iter->next)
     {
       MetaWindow *window = iter->data;
       pid_t pid = meta_window_get_pid (window);