drd/tests/std_thread: Enable this test program

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14001 a5019735-40e9-0310-863c-91ae7b9d1cf9
drd/tests/std_thread: Minimize diffs with original

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14002 a5019735-40e9-0310-863c-91ae7b9d1cf9