llvm/test/CodeGen/X86/vec_ctbits.ll: Add explicit -mtriple=x86_64-unknown. It was incompatible to Win32 x64.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217683 91177308-0d34-0410-b5e6-96231b3b80d8