Change VG_(allocEltDedupPA) to return a pointer to const. The reason is
that once an element has been allocated and added to the pool it must
not be modified afterwards. See the documentation in pub_tool_deduppoolalloc.h
The rest of the patch is ripple.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14654 a5019735-40e9-0310-863c-91ae7b9d1cf9