test::Multiprocess: exit cleanly from children with _exit()

util/test/multiprocess_posix.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 194 matching lines @@
   MultiprocessChild();
 
   info_->pipe_c2p_write.reset();
   info_->pipe_p2c_read.reset();
 
   if (testing::Test::HasFailure()) {
     // Trigger the ScopedForbidReturn destructor.
     return;
   }
 
-  exit(0);
+  // In a forked child, exit() is unsafe. Use _exit() instead.
+  _exit(EXIT_SUCCESS);
 }
 
 }  // namespace test
 }  // namespace crashpad