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/branches/WX_2_8_BRANCH@51592 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/utils.h

@@ -720,9 +720,16 @@ void WXDLLEXPORT wxGetMousePosition( int* x, int* y );
 // wxYield(): these functions are obsolete, please use wxApp methods instead!
 // ----------------------------------------------------------------------------
 
+// avoid redeclaring this function here if it had been already declated by
+// wx/app.h, this results in warnings from g++ with -Wredundant-decls
+#ifndef wx_YIELD_DECLARED
+#define wx_YIELD_DECLARED
+
 // Yield to other apps/messages
 WXDLLIMPEXP_BASE bool wxYield();
 
+#endif // wx_YIELD_DECLARED
+
 // Like wxYield, but fails silently if the yield is recursive.
 WXDLLIMPEXP_BASE bool wxYieldIfNeeded();