Explicitly state triple in machine-size-remarks.ll

A bot was unhappy with the x86 triple there before. Set it explicitly to
x86_64-apple-darwin just to get something consistent.

Example failure:
http://lab.llvm.org:8011/builders/llvm-hexagon-elf/builds/16846

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341882 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed