Move the WordFM (AVL trees of UWord-pairs) implementation from
helgrind/ into the core.  It's just too darn useful to not be in the
core.  There is some overlap in functionality between OSet and WordFM,
but OSet is more space efficient in some circumstances, whereas WordFM
is easier to use and a bit more flexible in some cases.

Also in this new module (m_wordfm) is a type WordBag, build on top of
WordFM.  This provides Multiset of UWords functionality.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8524 a5019735-40e9-0310-863c-91ae7b9d1cf9
8 files changed