Fix generic wxWindow when used in toolbar

GtkToolbar uses item minimum size as actual size, so don't use 0 as minimum
for toolbar children.

See #17756, #17704

(cherry picked from commit 2155eb2fde)

src/gtk/win_gtk.cpp

@@ -230,7 +230,12 @@ static void pizza_adjust_size_request(GtkWidget* widget, GtkOrientation orientat
     parent_class->adjust_size_request(widget, orientation, minimum, natural);
     // Override adjustments to minimum size. GtkWidgetClass.adjust_size_request()
     // will use the size request, if set, as the minimum.
-    *minimum = 0;
+    // But don't override if in a GtkToolbar, it uses the minimum as actual size.
+    GtkWidget* parent = gtk_widget_get_parent(widget);
+    if (parent)
+        parent = gtk_widget_get_parent(parent);
+    if (!GTK_IS_TOOL_ITEM(parent))
+        *minimum = 0;
 }
 
 // Needed to implement GtkScrollable interface, but we don't care about the