message: Use `not` to invert return code in expected to fail tests
  Windows does not like the RUN command of `(... || true) | ...`.
diff: -// RUN: (mlir-tblgen -gen-rewriters -I %S/../../include %s 2>&1 || true) | FileCheck %s
  +// RUN: not mlir-tblgen -gen-rewriters -I %S/../../include %s 2>&1 | FileCheck %s
  include "mlir/IR/OpBase.td"
  