More effective breakdown of memcpy into repeated load/store. These are now

More effective breakdown of memcpy into repeated load/store.  These are now
in the order lod;lod;lod;sto;sto;sto which means the load-store optimizer
has a better chance of producing ldm/stm.  Ideally you would get cooperation
from the RA as well but this is not there yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37179 91177308-0d34-0410-b5e6-96231b3b80d8