llvm/test/CodeGen/X86/Atomics-64.ll: Tweak for 2nd RUN not to overwrite %t. It sometimes causes spurious failure on lit win32.

Feel free to prune or suppress each output.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172823 91177308-0d34-0410-b5e6-96231b3b80d8