VERSION: Disable GIT_SNAPSHOT for the 4.9.3 release.

VERSION: Disable GIT_SNAPSHOT for the 4.9.3 release.

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>