Don't modify memory access right when changing data in debug stub.

tests/gdb/call_from_gdb.py

Index: tests/gdb/call_from_gdb.py
===================================================================
--- tests/gdb/call_from_gdb.py	(revision 0)
+++ tests/gdb/call_from_gdb.py	(revision 0)
@@ -0,0 +1,18 @@
+# -*- python -*-
+# Copyright (c) 2012 The Native Client Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import gdb_test
+import os
+
+
+def test(gdb):
+  gdb.Command('break main')
+  assert gdb.ResumeCommand('continue')['reason'] == 'breakpoint-hit'
+  assert gdb.Eval('test_call_from_gdb(1)') == '3'
+  assert gdb.Eval('global_var') == '2'
+
+
+if __name__ == '__main__':
+  gdb_test.RunTest(test, 'call_from_gdb', os.environ['GDB_TEST_GUEST'])