Set close-on-exec flag on pipe() and kqueue() file descriptors on MacOS

runtime/bin/process_macos.cc

Index: runtime/bin/process_macos.cc
diff --git a/runtime/bin/process_macos.cc b/runtime/bin/process_macos.cc
index 6256b31b88b024290f41e22167e5f1db6baf7bd3..f2d5ca3a8ea7a170c0d6dec54b24b54828f2aacc 100644
--- a/runtime/bin/process_macos.cc
+++ b/runtime/bin/process_macos.cc
@@ -124,6 +124,8 @@ class ExitCodeHandler {
     if (result < 0) {
       return false;
     }
+    FDUtils::SetCloseOnExec(sig_chld_fds_[0]);
+    FDUtils::SetCloseOnExec(sig_chld_fds_[1]);
 
     // Start thread that polls the pipe and handles process exits when
     // data is received on the pipe.
@@ -480,6 +482,8 @@ int Process::Start(const char* path,
     Log::PrintErr("Error pipe creation failed: %s\n", *os_error_message);
     return errno;
   }
+  FDUtils::SetCloseOnExec(event_fds[0]);
+  FDUtils::SetCloseOnExec(event_fds[1]);
 
   ProcessInfoList::AddProcess(pid, event_fds[1]);
   *exit_event = event_fds[0];