tcptls.c: Cleanup TCP/TLS listener thread on abnormal exit.

Temporarily running out of file descriptors should not terminate the
listener thread.  Otherwise, when there becomes more file descriptors
available, nothing is listening.

* Added EMFILE exception to abnormal thread exit.

* Added an abnormal TCP/TLS listener exit error message.

* Closed the TCP/TLS listener socket on abnormal exit so Asterisk does not
appear dead if something tries to connect to the socket.

ASTERISK-26903 #close

Change-Id: I10f2f784065136277f271159f0925927194581b5