RFR: 8274524: SSLSocket.close() hangs if it is called during the ssl handshake [v3]

[Alexey Bakhtin]

> Please review the patch for JDK-8274524
> 
> The fix just adds locks around InputStream read and skip operations to prevent concurrent read from socket.
> sun/security/ssl jtreg tests passed
> api/javax_net/ssl/SSLSocket/setUseClientMode jck test passed

Alexey Bakhtin has updated the pull request incrementally with one additional commit since the last revision:

  Add ClientSocketCloseHang jtreg test

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5760/files
  - new: https://git.openjdk.java.net/jdk/pull/5760/files/065073d1..145149bc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5760&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5760&range=01-02

  Stats: 134 lines in 1 file changed: 134 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5760.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5760/head:pull/5760

PR: https://git.openjdk.java.net/jdk/pull/5760