mc_LOADVn_slow: also allow --partial-loads-ok=yes to grant an
exemption for aligned 32 bit loads on 64 bit targets, since it appears
to be necessary.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13672 a5019735-40e9-0310-863c-91ae7b9d1cf9