Remove DTLS protocol

This was an experimental, undocumented protocol and I have no idea
whether it would be useful or not. Let's revisit if there's an
actual interest in this kind of stuff.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

Author: sustrik

Makefile.am

@@ -86,7 +86,6 @@ endif
 if DILL_SOCKETS
 if HAVE_TLS
 libdill_la_SOURCES += \
-    dtls.c \
     tls.c
 endif
 endif
@@ -151,7 +150,6 @@ endif
 if DILL_SOCKETS
 if HAVE_TLS
 check_PROGRAMS += \
-    tests/dtls \
     tests/tls
 endif
 endif