[MemCpyOpt] Don't emit IR in an unspecified order

Argument evaluation order is one of the edge cases where Clang differs
from GCC, yielding different IR depending on which compiler LLVM was
built with. Make the order deterministic and tune the test to actually
verify the order instead of trying to hide it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286126 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed