RFR: JDK-8277795: ldap connection timeout not honoured under contention [v3]

[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 one additional commit since the last revision:

  Allow the test to pass on MacOSX

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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/1b679497..7c277622

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6568&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6568&range=01-02

  Stats: 22 lines in 1 file changed: 10 ins; 1 del; 11 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