connect() to TCP name server has long timeout

[mdavidsaver]

An issue introduced by my addition of name lookup via. TCP. If a name server is not reachable, but there is a route, then the connect() will stall for a long time. This can stall cs-studio startup as the initial connection attempt is done during Context initialization.

This is only an issue if name servers are used other than localhost (eg. ssh tunnel).

"PVMgr JCADataSource Worker 1" #39 daemon prio=5 os_prio=0 tid=0x00007f23d9e21000 nid=0xd69 runnable [0x00007f235115f000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.Net.connect0(Native Method)
        at sun.nio.ch.Net.connect(Net.java:454)
        at sun.nio.ch.Net.connect(Net.java:446)
        at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:648)
        - locked <0x00000000eb5854e0> (a java.lang.Object)
        - locked <0x00000000eb585500> (a java.lang.Object)
        - locked <0x00000000eb5854f0> (a java.lang.Object)
        at java.nio.channels.SocketChannel.open(SocketChannel.java:189)
        at com.cosylab.epics.caj.impl.CAConnector.tryConnect(CAConnector.java:179)
        at com.cosylab.epics.caj.impl.CAConnector.connect(CAConnector.java:94)
        at com.cosylab.epics.caj.CAJContext.getTransport(CAJContext.java:1533)
        at com.cosylab.epics.caj.impl.CAJNameClient.connect(CAJNameClient.java:34)
        at com.cosylab.epics.caj.CAJContext.initializeNameServers(CAJContext.java:777)
        at com.cosylab.epics.caj.CAJContext.internalInitialize(CAJContext.java:763)
        at com.cosylab.epics.caj.CAJContext.initialize(CAJContext.java:697)
        - locked <0x00000000eb33dfa0> (a com.cosylab.epics.caj.CAJContext)
        at com.cosylab.epics.caj.CAJContext.checkState(CAJContext.java:680)
        - locked <0x00000000eb33dfa0> (a com.cosylab.epics.caj.CAJContext)
        at com.cosylab.epics.caj.CAJContext.createChannel(CAJContext.java:966)
        at org.diirt.support.ca.JCAChannelHandler.connect(JCAChannelHandler.java:169)
        - locked <0x00000000eb38f480> (a org.diirt.support.ca.JCAChannelHandler)
        at org.diirt.datasource.MultiplexedChannelHandler.guardedConnect(MultiplexedChannelHandler.java:313)
        at org.diirt.datasource.MultiplexedChannelHandler.addReader(MultiplexedChannelHandler.java:247)
        - locked <0x00000000eb38f480> (a org.diirt.support.ca.JCAChannelHandler)
        at org.diirt.datasource.DataSource$1.run(DataSource.java:178)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

   Locked ownable synchronizers:
        - <0x00000000eb398828> (a java.util.concurrent.ThreadPoolExecutor$Worker)