Suppress bogus g++ warnings about uninitialized variables.

The variables are always initialized but for some reason (at least the Apple
version of) g++ gives warnings for them.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64665 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/propgrid/propgrid.cpp

@@ -3047,8 +3047,8 @@ void FormMain::OnCatColours( wxCommandEvent& event )
 
 void FormMain::OnSelectStyle( wxCommandEvent& WXUNUSED(event) )
 {
-    int style;
+    int style = 0;
-    int extraStyle;
+    int extraStyle = 0;
 
     {
         wxArrayString chs;