LGTM, thanks. May I ask to fast-track this cleanup? AFAICS this is the only reference to STEPMAKE_LIBTOOL and I have some further cleanups (IEEE-conformance compiler flags, STEPMAKE_DLOPEN, STEPMAKE_MAN, and --with-lang=LANG) that would conflict. I couldn't push this earlier because of conflicts with #5794 and otherwise I'd have to wait another countdown period.
https://codereview.appspot.com/571790044/
