changes chooseproc behavior so that we start from master+1 pid

right now with addprocs(>3) we start allocating work to process
pid 3 before wrapping around.  This change just starts allocating work
to process 2 (worker 1) which should be more intuitive. See #8105.
Merge pull request #8123 from JuliaLang/jcb/fix8105

changes chooseproc behavior so that we start from master+1 pid