Qt: Free MainWindow at shutdown

MainWindow is allocated on heap on startup but not freed on shutdown.
Free the object at shutdown mainly to silent Valgrind.

When at it also fix two problems with the MainWindow destructor:
- Deleting main_ui_ triggers a currentChanged signal which in turn
  calls mainStackChanged that references the freed main_ui_ object.
  Prevent use after free error by disconnecting from the signal before
  freeing.

- Explicitly free file_set_dialog_ as no rparent perform the cleanup.

Bug: 14071
Change-Id: I9c1fbef04cf68bfffffea57ef298f4896d6583f9
Reviewed-on: https://code.wireshark.org/review/23739
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/wireshark-qt.cpp b/wireshark-qt.cpp
index 61fac58a59..538994daef 100644
--- a/wireshark-qt.cpp
+++ b/wireshark-qt.cpp
@@ -939,6 +939,7 @@ int main(int argc, char *qt_argv[])
 
     ret_val = wsApp->exec();
 
+    delete main_w;
     recent_cleanup();
     epan_cleanup();