Avoid outputting the assert message twice in non-GUI code.

As we always log the assert message in ::ShowAssertDialog() itself there is no
need to log it again in wxAppTraitsBase::ShowAssertDialog().

Also show the "please wait while generating stack trace information" in
wxAppTraitsBase::GetAssertStackTrace() itself instead of doing it in both
places which call it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62844 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/appcmn.cpp

@@ -465,11 +465,6 @@ bool wxGUIAppTraitsBase::ShowAssertDialog(const wxString& msg)
         wxString msgDlg = msg;
 
 #if wxUSE_STACKWALKER
-        // on Unix stack frame generation may take some time, depending on the
-        // size of the executable mainly... warn the user that we are working
-        wxFprintf(stderr, wxT("[Debug] Generating a stack trace... please wait"));
-        fflush(stderr);
-
         const wxString stackTrace = GetAssertStackTrace();
         if ( !stackTrace.empty() )
             msgDlg << wxT("\n\nCall stack:\n") << stackTrace;