[HEADSUP] please hold off sending PRs about removal of USE_REINPLACE for now

[Mark Linimon]

Rather than having dozens (or more) of individual PRs about this now-useless
construct, please hold off for now.  It will be better to do all of these in
one big sweep.  Also, there is a large patchset to unify all libtool
versions in process, and multiple commits of this form would just make it
harder to keep it up to date.  Thanks.

mcl