implemented notifications of the child process termination (patch 1494439)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39407 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/x11/evtloop.cpp

@@ -430,6 +430,9 @@ bool wxEventLoop::Dispatch()
 {
     XEvent event;
 
+    // Start off by checking if any of our child processes have finished.
+    wxCheckForFinishedChildren();
+
     // TODO allowing for threads, as per e.g. wxMSW
 
     // This now waits until either an X event is received,