RFR: 8288895: LdapContext doesn't honor set referrals limit [v2]

[rmartinc]

> Fixes [JDK-8288895](https://bugs.openjdk.org/browse/JDK-8288895).
> 
> Any `LimitExceededException` now quits the referral loop.
> 
> Added class `ReferralLimitSearchTest`. It is a simple jtreg test which checks that `java.naming.ldap.referral.limit` is really enforced. The dummy ldap server always returns a referral for any search query. If the number of searches exceeds the limit, it throws an `IOException` and the test fails.
> 
> 
> make test TEST=jtreg:jdk/com/sun/jndi/ldap/ReferralLimitSearchTest.java

rmartinc has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  8288895: LdapContext doesn't honor set referrals limit

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9256/files
  - new: https://git.openjdk.org/jdk/pull/9256/files/a04d123c..09961af7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9256&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9256&range=00-01

  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/9256.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9256/head:pull/9256

PR: https://git.openjdk.org/jdk/pull/9256