Add libtest_missing_symbol_child_private.

Bug: http://b/77236525
Bug: http://b/77276121
Test: builds

(cherry picked from commit 06d31c94c280aa8b8b2b043892f78acfbe86dce9)

Change-Id: I6f4b6d2527c8146a252aaa935a46d09632c44a5f
diff --git a/tests/Android.bp b/tests/Android.bp
index 83172da..70e0d54 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -533,6 +533,7 @@
         "libtest_init_fini_order_root2",
         "libtest_init_fini_order_root",
         "libtest_missing_symbol_child_public",
+        "libtest_missing_symbol_child_private",
         "libtest_missing_symbol_root",
         "libtest_missing_symbol",
         "libtest_nodelete_1",