WHATSNEW: Add release notes for Samba 4.9.3.
o CVE-2018-14629 (Unprivileged adding of CNAME record causing loop in AD
Internal DNS server)
o CVE-2018-16841 (Double-free in Samba AD DC KDC with PKINIT)
o CVE-2018-16851 (NULL pointer de-reference in Samba AD DC LDAP server)
o CVE-2018-16852 (NULL pointer de-reference in Samba AD DC DNS servers)
o CVE-2018-16853 (Samba AD DC S4U2Self crash in experimental MIT Kerberos
configuration (unsupported))
o CVE-2018-16857 (Bad password count in AD DC not always effective)
Signed-off-by: Karolin Seeger <kseeger@samba.org>