more on portability, following a gMCP submission

git-svn-id: https://svn.r-project.org/R/trunk@63340 00db46b3-68df-0310-9c12-caf00c1e9a41
some updates

git-svn-id: https://svn.r-project.org/R/trunk@63342 00db46b3-68df-0310-9c12-caf00c1e9a41