mcjoin: Fix buggy behaviour for --restart causing loss of multicast stream

After the recent refactor, and possibly even earlier, the mcjoin tool
did not handle --restart=N well.  Instead of rejoining the stream every
N seconds, to work around restrictions regarding the default route, the
code joined only for one second before closing the socket, causing the
kernel to send leave immediately.  For most previous use cases this did
nothing, since mcjoin has been used with earlier versions of WeOS IGMP
snooping, which up to this point ignores Leave messages.

Fix is to sleep N full seconds before closing socket and rejoining.

Also, a bit of refactoring and cleanup of warning messages in build.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
mcjoin: Add debian/ directory for building .deb package.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>