[RFR] 8160768: Add capability to custom resolve host/domain names within the default JDNI LDAP provider

[Rob McKenna]

Hi folks,

I'm looking for feedback on this suggested fix for the following bug:

https://bugs.openjdk.java.net/browse/JDK-816076
http://cr.openjdk.java.net/~robm/8160768/webrev.01/

This is something that has come up a few times. Basically in certain
environments (e.g. MS Active Directory) there is a dependence on
DNS records to provide a pointer to the actual ldap server to be used
for a given LdapCtx.PROVIDER_URL where the url itself simply points to the
domain name.

This fix add a new Ldap context property which allows a user to specify a
class (implementing BiFunction) which can perform any necessary extra steps
to derive the ldap servers hostname/port from the PROVIDER_URL.

    -Rob