if on OpenSSL 1.1.1 or later.
We trust OpenSSL 1.1.1 and later to be good enough to handle all
the reference counting and freeing nowadays, which is something that
was not done correctly in (much) older OpenSSL versions, leading
to crashes on one hand and on memory leaks on the other hand.
In OpenSSL 1.1.0 and earlier we do not rehash tls on simple "REHASH",
since that code has not been vetted. However, nobody should be
running those old OpenSSL versions anyway, since they are out of
official OpenSSL support.
Bram Matthys
79740c4a38