The only generated code difference is that now we call memcpy when
the size of the array is unknown. This matches GCC behavior and is
better since the run time value can be arbitrarily large.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42433 91177308-0d34-0410-b5e6-96231b3b80d8
