report obsolete POSIX function rand_r

git-svn-id: https://svn.r-project.org/R/trunk@66510 00db46b3-68df-0310-9c12-caf00c1e9a41
another example of over-loading

git-svn-id: https://svn.r-project.org/R/trunk@66511 00db46b3-68df-0310-9c12-caf00c1e9a41