r25218: After discussion with Simo, remove the subclass support from LDB.

r25218: After discussion with Simo, remove the subclass support from LDB.

Subclass support was designed to avoid needing to spell out the full
list of objectClasses that an entry was in.  However, Samba4 now
enforces this restriction in the objectClass module, and the way
subclass matching was handled was complex and counter-intuitive in my
opinion (and did not match LDAP).

Andrew Bartlett
(This used to be commit f5ce04b904e14445a2a7e7f92e7e1f64b645c6f2)