Remove unnecessary check from DoNativeBeforeUpdate()

Don't test if we're using the native task dialog in this function
because it is only called if we are, so simplify the code by omitting
this check.

src/msw/progdlg.cpp

@@ -511,8 +511,6 @@ bool wxProgressDialog::Pulse(const wxString& newmsg, bool *skip)
 bool wxProgressDialog::DoNativeBeforeUpdate(bool *skip)
 {
 #ifdef wxHAS_MSW_TASKDIALOG
-    if ( HasNativeTaskDialog() )
-    {
     wxCriticalSectionLocker locker(m_sharedData->m_cs);
 
     if ( m_sharedData->m_skipped  )
@@ -529,13 +527,12 @@ bool wxProgressDialog::DoNativeBeforeUpdate(bool *skip)
         m_timeStop = m_sharedData->m_timeStop;
 
     return m_sharedData->m_state != Canceled;
-    }
-#endif // wxHAS_MSW_TASKDIALOG
-
+#else // !wxHAS_MSW_TASKDIALOG
     wxUnusedVar(skip);
     wxFAIL_MSG( "unreachable" );
 
     return false;
+#endif // wxHAS_MSW_TASKDIALOG/!wxHAS_MSW_TASKDIALOG
 }
 
 void wxProgressDialog::Resume()