IO: Fix error in Process exit handling.

runtime/bin/process_macos.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/process.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
 #include <signal.h>
@@ skipping 197 matching lines @@
       }
     }
   }
 
 
   // Entry point for the separate exit code handler thread started by
   // the ExitCodeHandler.
   static void ExitCodeHandlerEntry(uword param) {
     struct pollfd pollfds;
     pollfds.fd = param;
-    pollfds.events |= POLLIN;
+    pollfds.events = POLLIN;
     while (true) {
       int result = TEMP_FAILURE_RETRY(poll(&pollfds, 1, -1));
       if (result == -1) {
         ASSERT(EAGAIN == EWOULDBLOCK);
         if (errno != EWOULDBLOCK) {
           perror("ExitCodeHandler poll failed");
         }
       } else {
         // Read the byte from the wake-up fd.
         ASSERT(result = 1);
@@ skipping 326 matching lines @@
   if (result == -1) {
     return false;
   }
   return true;
 }
 
 
 void Process::TerminateExitCodeHandler() {
   ExitCodeHandler::TerminateExitCodeThread();
 }