Merge revisions 14216,14591,14593 from the BUF_REMOVAL branch to trunk.
Chang the semantics of VG_(getgroups) to support querying the number
of supplementary group IDs which simplifies obtaining them and gets
rid of fixed size buffers.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14594 a5019735-40e9-0310-863c-91ae7b9d1cf9