drd: Add semaphore annotations (#333072)

This is a slightly modified version of a patch from Ivo Raisr <ivosh@ivosh.net>


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13984 a5019735-40e9-0310-863c-91ae7b9d1cf9
NEWS: Add #333072

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13985 a5019735-40e9-0310-863c-91ae7b9d1cf9