Remove the valgrind_support parameter from LibVEX_Init. It's unused
and looks like an anachronism. VEX is also cleaner without valgrind things
creeping in.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2955 8f6e269a-dfd6-0310-a8e1-e2731360e62c