Add a test for external/stlport a6df82320fcb8f26af0d067c7768fedbaeb9ad88.

Change-Id: If4df9f5df41ae5453a3dff6bb032b419819f8703
diff --git a/tests/Android.mk b/tests/Android.mk
index e8ee687..b32d8d4 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -67,6 +67,7 @@
     string_test.cpp \
     strings_test.cpp \
     stubs_test.cpp \
+    sstream_test.cpp \
     sys_epoll_test.cpp \
     sys_mman_test.cpp \
     sys_resource_test.cpp \