extracted GUI-specific part of utilsunx.cpp to a new unix/apptraits.cpp file and don't include utilsunx.cpp in both base and GUI libraries now so that we can get rid of BASE_AND_GUI_UNIX_SRC in files.bkl entirely

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52676 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/apptbase.h

@@ -69,6 +69,12 @@ public:
     // here and not in wxConsoleAppTraits)
     virtual GSocketManager *GetSocketManager();
 #endif
+
+protected:
+    // a helper for the implementation of WaitForChild() in wxGUIAppTraits:
+    // checks the streams used for redirected IO in execData and returns true
+    // if there is any activity in them
+    bool CheckForRedirectedIO(wxExecuteData& execData);
 };
 
 #endif // _WX_UNIX_APPTBASE_H_