tls: add vlc_tls_Close() helper
tls: add vlc_tls_Close() helper

In most cases... actually in all cases that I know of, the TCP
connection underneath the TLS session is closed at the same time.

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc