don't redeclare wxYield() if it had been already declared to fix g++ warnings with -Wredundant-decls

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51592 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/app.h

@@ -633,9 +633,16 @@ protected:
 // Force an exit from main loop
 extern void WXDLLIMPEXP_BASE wxExit();
 
+// avoid redeclaring this function here if it had been already declated by
+// wx/utils.h, this results in warnings from g++ with -Wredundant-decls
+#ifndef wx_YIELD_DECLARED
+#define wx_YIELD_DECLARED
+
 // Yield to other apps/messages
 extern bool WXDLLIMPEXP_BASE wxYield();
 
+#endif // wx_YIELD_DECLARED
+
 // Yield to other apps/messages
 extern void WXDLLIMPEXP_BASE wxWakeUpIdle();