[pygobject/wip/jfelder/gtk4-toolbutton: 2/2] gtk overrides: Drop Gtk.main for Gtk4

[Jean Felder <jfelder src gnome org>]

commit 2b3154e394ee50bd342abe780cbe0fa0af95a9c6
Author: Jean Felder <jean felder gmail com>
Date:   Mon Mar 16 20:46:17 2020 +0100

    gtk overrides: Drop Gtk.main for Gtk4
    
    It has been removed (gtk commit 4dd780a96b1d37903ab88a4ae4536329cd9e164e)

 gi/overrides/Gtk.py | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)
---
diff --git a/gi/overrides/Gtk.py b/gi/overrides/Gtk.py
index 74555d16..b4213642 100644
--- a/gi/overrides/Gtk.py
+++ b/gi/overrides/Gtk.py
@@ -1614,22 +1614,20 @@ if Gtk._version == '3.0':
     Menu = override(Menu)
     __all__.append('Menu')
 
-_Gtk_main_quit = Gtk.main_quit
-
-
-@override(Gtk.main_quit)
-def main_quit(*args):
-    _Gtk_main_quit()
-
+if Gtk._version in ("2.0", "3.0"):
+    _Gtk_main_quit = Gtk.main_quit
 
-_Gtk_main = Gtk.main
+    @override(Gtk.main_quit)
+    def main_quit(*args):
+        _Gtk_main_quit()
 
+    _Gtk_main = Gtk.main
 
-@override(Gtk.main)
-def main(*args, **kwargs):
-    with register_sigint_fallback(Gtk.main_quit):
-        with wakeup_on_signal():
-            return _Gtk_main(*args, **kwargs)
+    @override(Gtk.main)
+    def main(*args, **kwargs):
+        with register_sigint_fallback(Gtk.main_quit):
+            with wakeup_on_signal():
+                return _Gtk_main(*args, **kwargs)
 
 
 if Gtk._version in ("2.0", "3.0"):