DISPATCH-1825: Skip TCP self test if selectors module is absent
DISPATCH-1825: Skip TCP self test if selectors module is absent

Create dummy echo client and server modules if import fails due to
lack of 'selectors'.

Skip tests if import of selectors fails

ChugR/qpid-dispatch,apache/dispatch,apache/qpid-dispatch,ganeshmurthy/qpid-dispatch,ChugR/qpid-dispatch,apache/dispatch,apache/dispatch,ErnieAllen/qpid-dispatch,ganeshmurthy/qpid-dispatch,ted-ross/qpid-dispatch,kgiusti/dispatch,mgoulish/qpid-dispatch,ted-ross/qpid-dispatch,kgiusti/dispatch,mgoulish/qpid-dispatch,apache/dispatch,mgoulish/qpid-dispatch,mgoulish/qpid-dispatch,apache/qpid-dispatch,apache/qpid-dispatch,apache/dispatch,apache/qpid-dispatch,kgiusti/dispatch,ted-ross/qpid-dispatch,ganeshmurthy/qpid-dispatch,ted-ross/qpid-dispatch,ganeshmurthy/qpid-dispatch,ErnieAllen/qpid-dispatch,apache/dispatch,ChugR/qpid-dispatch,ChugR/qpid-dispatch,apache/qpid-dispatch,ted-ross/qpid-dispatch,apache/dispatch,apache/qpid-dispatch,ganeshmurthy/qpid-dispatch,kgiusti/dispatch,ChugR/qpid-dispatch,ErnieAllen/qpid-dispatch,ChugR/qpid-dispatch,ErnieAllen/qpid-dispatch,mgoulish/qpid-dispatch,ErnieAllen/qpid-dispatch,kgiusti/dispatch,mgoulish/qpid-dispatch,ErnieAllen/qpid-dispatch,kgiusti/dispatch,ted-ross/qpid-dispatch,ganeshmurthy/qpid-dispatch