llvm/test/Other/close-stderr.ll: Mark it as XFAIL:mingw32 for now.

On MSYS, 70 is not seen, but 1.

r127726 should be reworked. Candidate options are;

  1) Use not exit(70), but _exit(70), in report_fatal_error().
  2) Return with _exit(70) in ~raw_ostream().

llvm-svn: 167836