Fix two register leaks in the trusted->untrusted context switch

tests/syscall_return_regs/nacl.scons

Index: tests/syscall_return_regs/nacl.scons
diff --git a/tests/syscall_return_regs/nacl.scons b/tests/syscall_return_regs/nacl.scons
new file mode 100644
index 0000000000000000000000000000000000000000..4c50d692ed4f5b8d386a7fc8e80402c3a9a1bed9
--- /dev/null
+++ b/tests/syscall_return_regs/nacl.scons
@@ -0,0 +1,16 @@
+# -*- 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('env')
+
+if not env.AllowInlineAssembly():
+  Return()
+
+nexe = env.ComponentProgram(
+    'syscall_return_regs_test', ['syscall_return_regs_test.c'],
+    EXTRA_LIBS=['${NONIRT_LIBS}', 'test_common'])
+
+node = env.CommandSelLdrTestNacl('syscall_return_regs_test.out', nexe)
+env.AddNodeToTestSuite(node, ['small_tests'], 'run_syscall_return_regs_test')