Quick fix to test/CodeGen/2007-06-18-SextAttrAggregate.c for x86_64-mingw32, corresponding to r216507.

FIXME: Explicit triplets might be given here.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@216557 91177308-0d34-0410-b5e6-96231b3b80d8