Remove unneeded check in SPNEGO initiator

In init_ctx_cont, if the response token contains no fields, we set a
return value but don't actually quit out of the function.  We do not
need this check (we will fail later on if a piece of required
information isn't present), so just remove it.  Reported by
simo@redhat.com.
Fix memory leak in SPNEGO initiator

If we eliminate a mechanism from the initiator list because
gss_init_sec_context fails, free the memory for that mech OID before
removing it from the list.

[ghudson@mit.edu: clarified commit message]

ticket: 7803 (new)
target_version: 1.12.1
tags: pullup