Revert the part of 64623 that attempted to align the source in a

Revert the part of 64623 that attempted to align the source in a
memcpy to match the alignment of the destination. It isn't necessary
for making loads and stores handled like the SSE loadu/storeu
intrinsics, and it was causing a performance regression in
MultiSource/Applications/JM/lencod.

The problem appears to have been a memcpy that copies from some
highly aligned array into an alloca; the alloca was then being
assigned a large alignment, which required codegen to perform
dynamic stack-pointer re-alignment, which forced the enclosing
function to have a frame pointer, which led to increased spilling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65289 91177308-0d34-0410-b5e6-96231b3b80d8