mptcpd for Debian

There are comments for each specific rule in debian/rules.

The project is providing a few different binaries:

- a daemon: mptcpd in usr/libexec because a systemd service starts it

- a lib to help building plugins: libmptcpd

- some plugins for mptcpd: .so in usr/lib/*/mptcpd

- a lib to be used with LD_PRELOAD to create MPTCP sockets instead of TCP ones:
  libmptcpwrap in usr/lib/*/mptcpize

- a tool to force apps using MPTCP sockets with libmptcpwrap: mptcpize

Some Lintian warnings/errors have been ignored, see comments in
*.lintian-overrides files.

 -- Matthieu Baerts <matttbe@kernel.org>  Thu, 28 Jul 2022 16:05:43 +0200