Fix overzealous SPNEGO src_name/deleg_cred release

Fix overzealous SPNEGO src_name/deleg_cred release

Commit 24b844714dea3e47b17511746b5df5b6ddf13d43 (ticket 8845) added
releases of sc->internal_name and sc->deleg_cred before calling the
underlying mech's gss_accept_sec_context(), to avoid a potential leak
if the mech reports a value multiple times.  Commit
c2ca2f26eaf817a6a7ed42257c380437ab802bd9 (ticket 8851) added a branch
which calls negoex_accept() instead of calling directly into the
underlying mech.  If negoex_accept() doesn't call into the mech on the
last acceptor leg, the src_name and deleg_cred values from the final
mech call are lost.

Move the releases to the non-NegoEx branch.  negoex_accept() already
does its own releases when it calls into the mech.

Reported by Luke Howard.

ticket: 8898 (new)
tags: pullup
target_version: 1.18-next