switched to use unit_test_result_saver for internal testing

switched to wrap_stringstream
test cases added for the NULL char strings comparisons


[SVN r16561]

libs/test

@@ -1 +1 @@
-Subproject commit 60a4c7dc8bf0fec2a6bf0a00149ef0b81b3e6bc3
+Subproject commit 5e4a970fa7949437c46e3cba44b9c7f69f42a142