Specify triple so 'make check' passes on darwin x86-64

The check lines were added with:
http://reviews.llvm.org/rL256458
http://reviews.llvm.org/rL256460

but on a darwin target, the output looks like:
  ## InlineAsm Start
  rorq  %rdi
  ## InlineAsm End
  ## InlineAsm Start
  rorq  %rsi
  ## InlineAsm End
  leaq  (%rsi,%rdi), %rax
  retq

llvm-svn: 256507