sso: zxid_validate_cond() now frees myentid.

All callers of zxid_validate_cond() pass myentid directly from
zxid_my_ent_id(), which allocates it dynamically, and none of
the callers use the value any further (or frees it).
simp: Fixed some leaks in zxid_simple_no_ses_cf().
meta: Fixed leak of entities in zxid_get_ent_ss().