RFR: JDK-8277795: ldap connection timeout not honoured under contention [v2]

[Rob McKenna]

> This fix attemps to resolve an issue where threads can stack up on each other while waiting to get a connection from the ldap pool to an unreachable server. It does this by having each thread start a countdown prior to holding the pools' lock. (which has been changed to a ReentrantLock) Once the lock has been grabbed, the timeout is adjusted to take the waiting time into account and the process of getting a connection from the pool or creating a new one commences.
> 
> Note: this fix also changes the meaning of the connection pools initSize somewhat. In a situation where we have a large initSize and a small timeout the first thread could actually exhaust the timeout before creating all of its initial connections. Instead this fix simply creates a single connection per pool-connection-request. It continues to do so for subsequent requests regardless of whether an existing unused connection is available in the pool until initSize is exhausted. As such it may require a CSR.

Rob McKenna has updated the pull request incrementally with two additional commits since the last revision:

 - JDK-8277795: whitespace
 - Add test

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6568/files
  - new: https://git.openjdk.java.net/jdk/pull/6568/files/61a7ae5b..1b679497

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6568&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6568&range=00-01

  Stats: 133 lines in 3 files changed: 131 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6568.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6568/head:pull/6568

PR: https://git.openjdk.java.net/jdk/pull/6568