Change process exit codes on Windows to always be positive

runtime/bin/process_win.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 "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include <process.h>  // NOLINT
 
 #include "bin/builtin.h"
@@ skipping 137 matching lines @@
     bool success = LookupProcess(pid, &handle, &wait_handle, &exit_pipe);
     if (!success) {
       FATAL("Failed to lookup process in list of active processes");
     }
     // Unregister the event in a non-blocking way.
     BOOL ok = UnregisterWait(wait_handle);
     if (!ok && GetLastError() != ERROR_IO_PENDING) {
       FATAL("Failed unregistering wait operation");
     }
     // Get and report the exit code to Dart.
-    int exit_code;
+    DWORD exit_code;
     ok = GetExitCodeProcess(handle,
                             reinterpret_cast<DWORD*>(&exit_code));
     if (!ok) {
       FATAL1("GetExitCodeProcess failed %d\n", GetLastError());
     }
-    int negative = 0;
-    if (exit_code < 0) {
-      exit_code = abs(exit_code);
-      negative = 1;
-    }
-    int message[2] = { exit_code, negative };
+    int message[2] = { exit_code, 0 };
     DWORD written;
     ok = WriteFile(exit_pipe, message, sizeof(message), &written, NULL);
     // If the process has been closed, the read end of the exit
     // pipe has been closed. It is therefore not a problem that
     // WriteFile fails with a closed pipe error
     // (ERROR_NO_DATA). Other errors should not happen.
     if (ok && written != sizeof(message)) {
       FATAL("Failed to write entire process exit message");
     } else if (!ok && GetLastError() != ERROR_NO_DATA) {
       FATAL1("Failed to write exit code: %d", GetLastError());
@@ skipping 666 matching lines @@
 
 
 intptr_t Process::CurrentProcessId() {
   return static_cast<intptr_t>(GetCurrentProcessId());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)