Fix up failing glibc tests.

There is a known bug running clone with the CLONE_VM flag, so for host
create an empty test.

Change the expected output of the stdio test for a glibc difference.

Change the pause test to use ScopedSignalHandler to setup/restore the SIGALRM
handler.

After this, running bionic-unit-tests-glibc passes for all tests.

Bug: 11389824

Change-Id: Ib304eae4164115835a54991dfdca5821ecc3db5e
diff --git a/tests/ScopedSignalHandler.h b/tests/ScopedSignalHandler.h
new file mode 100644
index 0000000..89a14a6
--- /dev/null
+++ b/tests/ScopedSignalHandler.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * 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,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _BIONIC_TESTS_SCOPED_SIGNAL_HANDLER_H
+#define _BIONIC_TESTS_SCOPED_SIGNAL_HANDLER_H
+
+#include <signal.h>
+
+class ScopedSignalHandler {
+ public:
+  ScopedSignalHandler(int signal_number, void (*handler)(int)) : signal_number_(signal_number) {
+    sigemptyset(&action_.sa_mask);
+    action_.sa_flags = 0;
+    action_.sa_handler = handler;
+    sigaction(signal_number_, &action_, &old_action_);
+  }
+
+  ~ScopedSignalHandler() {
+    sigaction(signal_number_, &old_action_, NULL);
+  }
+
+ private:
+  struct sigaction action_;
+  struct sigaction old_action_;
+  const int signal_number_;
+};
+
+#endif // _BIONIC_TESTS_SCOPED_SIGNAL_HANDLER_H