Restored support for some command line options on behalf of Debian.

Changes

• New --enable-compat option added to configure script. Enables support for command line options from v2.x used by vagrant-lxc, https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=824698#15
  • --laddr=SRC
  • --lport=PORT
  • --caddr=SRC
  • --cport=PORT

Fixes

• Portability fixes for musl libc