[X86] Layout tests exactly as update_llc_test_checks.py would

Put the LLVM IR at the bottom of the function instead of the top.  In my
next patch, I will run update_llc_test_checks.py on this file, and I
want to only highlight the diffs in the CHECK lines. Hopefully by doing
this change first, the patch will be more understandable.

llvm-svn: 338926