Incomplete Merge of http://review.couchbase.org/#/c/61942 in Master

Unfortunately the merge of http://review.couchbase.org/#/c/61942 into master was not complete.
In particular the function isDeadConnectionsEmpty() is not overloaded in DcpConnMap - a class in connmap.h

Without the overloaded function, the top-level function will be called, which will always return true, as the function is defined as follows in the base ConnMap class (see connmap.h):

 virtual bool isDeadConnectionsEmpty() {

        return true;

    }

This means the ConnManagerTask may be terminated before all entries have been removed from the deadConnectionsList. See http://src.couchbase.org/source/xref/trunk/ep-engine/src/connmap.cc#117

The function to be added to the DcpConnMap class is as follows:

 bool isDeadConnectionsEmpty() {

        return deadConnections.empty();

    }