Fix unload of recursively linked library

Expanded test for recursive libs. Fixed bug with unnecessary
  soinfo_free of already loaded library.

(cherry picked from commit a6ac54a215)

Change-Id: I6907c723d9fbdf6b2777f3f236b1e29b0843edd6

tests/libs/dlopen_testlib_invalid.cpp

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include <stdlib.h>
+
+// This file is used for libraries that are not supposed to
+// be successfully loaded/linked - therefore, this function should
+// not be visible via dlsym - (we are going to use this fact in tests)
+extern "C" int dlopen_test_invalid_function() {
+  abort();
+}