Correct fix for unaligned memcpy - malloc'ed memory incremented by sizeof(struct...

Correct fix for unaligned memcpy - malloc'ed memory incremented by sizeof(struct locking_data)
was not forced to be 8 byte aligned. Use union to force it to be correctly aligned
for memcpy and use void *, to tell compiler not to optimize aligned copy (this last fix
suggested by Trond @ RedHat). The first fix should be sufficient, but this provides a
"belt and braces" fix.
Jeremy.
(This used to be commit 22c5915bb466529ac1bcb5c2574888b360a9775b)