RFR: 8263743: redundant lock in SSLSocketImpl

[Xue-Lei Andrew Fan]

Remove redundant lock in SSLSocketImpl.

In the SSLSocketImpl, there is a socket level lock while reading application data (see readApplicationRecord). 

                socketLock.lock(); 
                try { 
                    plainText = decode(buffer); 
                } finally { 
                    socketLock.unlock(); 
                } 
If an application data read is in progress, other calling to SSLSocket APIs (for example getUseClientMode()) could be blocked if socket level locks are used. 

No new regression test.  Simple fix, hard to trigger the deadlock.

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Commit messages:
 - 8263743: redundant lock in SSLSocketImpl

Changes: https://git.openjdk.java.net/jdk/pull/3053/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3053&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263743
  Stats: 7 lines in 1 file changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3053.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3053/head:pull/3053

PR: https://git.openjdk.java.net/jdk/pull/3053