RFR: JDK-8282686: Add constructors taking a cause to SocketException [v2]

[Joe Darcy]

> Please review this small API enhancement to add the usual constructors taking a cause to SocketException and then update uses of initiCause on creating SocketException to instead pass the cause via the constructor.
> 
> Please also review the CSR: https://bugs.openjdk.java.net/browse/JDK-8282688

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Add regression test.
 - Merge branch 'master' into JDK-8282686
 - JDK-8282686: Add constructors take a cause to SocketException

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7705/files
  - new: https://git.openjdk.java.net/jdk/pull/7705/files/e65f9ae5..978b379d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7705&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7705&range=00-01

  Stats: 8268 lines in 175 files changed: 6072 ins; 1565 del; 631 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7705.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7705/head:pull/7705

PR: https://git.openjdk.java.net/jdk/pull/7705