test/CodeGen/X86/avx-minmax.ll: Unbreak Win32.

On Windows x64, 128-bit arguments are not passed by reg but by indirect. eg.

maxpd:
        vmovapd (%rcx), %xmm0
        vmaxpd  (%rdx), %xmm0, %xmm0

FIXME: I don't care YMM on x64 for now.
llvm-svn: 140143