...that had plagued 2e293a73 "new
loplugin/rewriter comparisonwithconstant" (in sal/osl/unx/pipe.cxx), and
auto-rewrite the remaining occurrences in sal (that the mentioned commit had
failed to address, for whatever reason)

Change-Id: I3dc3bae8dd92ba8bf576f6e06e7c9ee21f883661