Ignore symbols of imported libs' dependencies

When a library is present in a namespace via the secondary_namespaces
list (i.e. the executable, LD_PRELOAD, DF_1_GLOBAL, or
android_create_namespace inheritance), then we want to search that
library's symbols, but not the symbols of its dependencies. Otherwise,
we want to search the dependencies to handle cross-NS dependency.

Bug: http://b/148569846
Test: bionic unit tests
Change-Id: If798d69de28ed5c0f1a155e4ff85c7e08934e531
diff --git a/tests/libs/ns_hidden_child_app.cpp b/tests/libs/ns_hidden_child_app.cpp
new file mode 100644
index 0000000..01a95cc
--- /dev/null
+++ b/tests/libs/ns_hidden_child_app.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+
+__attribute__((weak)) extern "C" void public_function();
+__attribute__((weak)) extern "C" void internal_function();
+
+extern "C" void app_function() {
+  printf("public_function is %s\n", public_function == nullptr ? "null" : "non-null");
+  printf("internal_function is %s\n", internal_function == nullptr ? "null" : "non-null");
+}