Un-break the arm32 compilation pipeline following the change of
arity of Iop_Mul32Fx4, Iop_Sub32Fx4, Iop_Add32Fx4 in r2809.


git-svn-id: svn://svn.valgrind.org/vex/trunk@2840 8f6e269a-dfd6-0310-a8e1-e2731360e62c