call OnInit() from all samples to allow using standard command line options with all of them (patch 1623971)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@44354 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/help/demo.cpp

@@ -287,6 +287,9 @@ IMPLEMENT_APP(MyApp)
 // `Main program' equivalent: the program execution "starts" here
 bool MyApp::OnInit()
 {
+    if ( !wxApp::OnInit() )
+        return false;
+
     // Create a simple help provider to make SetHelpText() do something.
     // Note that this must be set before any SetHelpText() calls are made.
 #if USE_SIMPLE_HELP_PROVIDER