FCPPluginClient.sendSynchronous(): Don't reset timeout upon spurious
wakeup of Condition.await()

- This is done by using awaitNanos() instead which returns the
non-expired part of the timeout instead of swallowing it.
- Notice: The code of the Condition implementation which
ReentrantReadWriteLock uses seems to interally always use nanoseconds,
even for the non-nano await(). So this shouldn't be any slower. This is
also stressed by the JavaDoc of await() which says that it is the same
as awaitNanos(unit.toNanos(time)) > 0