[jdk11u-dev] RFR: 8274524: SSLSocket.close() hangs if it is called during the ssl handshake

[Alexey Bakhtin]

Backport of JDK-8274524 to JDK11u-dev
Backport is almost clean except for a trivial fix for Pattern Matching in the instanceof (not available in JDK11) and braces for the if-clauses.
sun/security/ssl/SSLSocketImpl tests passed

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Commit messages:
 - Backport 58dae60da0711c4ae0cb23f8ce2328e051d603b2

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/823/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=823&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274524
  Stats: 153 lines in 2 files changed: 153 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/823.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/823/head:pull/823

PR: https://git.openjdk.java.net/jdk11u-dev/pull/823