https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97865
--- Comment #12 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- config.sub and config.guess are imported, unmodified, from upstream config.git. libtool has lots of local changes, hopefully all of them submitted upstream but maybe not and maybe some not committed upstream (libtool has very few commits in recent years, but lots since the 2009 version used in GCC). As well as checking all the local changes (relative to libtool commit 2c9c38d8a12eb0a2ce7fe9c3862523026c3d5622, apparently) and applying them to a new version as needed, updating libtool would also require reverting libtool commit 3334f7ed5851ef1e96b052f2984c4acdbf39e20c to deal with a mismatch of --with-sysroot interpretations.
