negatives, by marking the V bits that come from out of range parts of
the access as undefined; and hence any use of them leads to an value
error. Prior to this they were marked as defined and could be used
without error.
Behaviour of --partial-loads-ok=no (the default case) is unchanged.
Also add some testing thereof.
Fixes#294523. Modified version of a patch and testcase by Patrick
J. LoPresti (lopresti@gmail.com).
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12430
