troubleshoot about compiling

The sys/fcntl.h is not a POSIX one. We do have fcntl.h header and all sys/*.h specified by OpenGroup, but not the Linux ones.
Just skip it on Haiku:

src/headers.h:92:
#ifdef HAVE_SYS_FCNTL_H
#include <sys/fcntl.h>
#endif /* HAVE_SYS_FCNTL_H */

And all will compile fine.
The testsuite compile failed, though.
So, I guess this software must be ported *and* patched, indeed.

Here what I've done quickly to build it (except testsuite) with gcc4:

cd anubis-4.1.1
$ cp /boot/common/share/libtool/config/config.* build/.
$ libtoolize --force --copy --install
...
$ configure --prefix=/boot/common
...
$ make
...

As stated, it failed in testsuite, but the anubis lib and binary build:

$ src/anubis --version
anubis (GNU Anubis 4.1.1)
Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008 The Anubis Team.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

$ src/anubis --help
Usage: anubis [OPTION]... 
SMTP message submission daemon.

  -b, --bind=[HOST:]PORT      Specify the TCP port on which GNU Anubis listens
                              for connections; the default HOST is INADDR_ANY,
                              and default PORT is 24 (private mail system)
  -r, --remote-mta=[HOST:]PORT
                              Specify a remote SMTP host name or IP address;
                              the default is 25
  -l, --local-mta=FILE        Execute a local SMTP server, which works on
                              standard input and output (inetd-type program);
                              this option excludes the `--remote-mta' option
  -m, --mode=MODE             Select operation mode; MODE is one of
                              "transparent", "auth" or "mda"
  -f, --foreground            Foreground mode
  --from=EMAIL                Specify sender address (implies MDA mode)
  -i, --stdio                 Use the SMTP protocol (OMP/Tunnel) as described
                              in RFC 821 on standard input and output

  Output options

  -s, --silent                Work silently
  -v, --verbose               Work noisily
  -D, --debug                 Debug mode

  Miscellaneous options

  --altrc=FILE                Specify alternate system configuration file
  --norc                      Ignore system configuration file
  -c, --check-config=DEBUG-LEVEL
                              Run the configuration file syntax checker
  --show-config-options       Print a list of configuration options used to
                              build GNU Anubis
  --relax-perm-check          Do not check user configuration file permissions
  --pid-file=FILE             Store the PID of the running daemon in FILE

  Other options

  -h, --help                  Give this help list
  --usage                     Give a short usage message
  --version                   Print program version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

Report bugs to <bug-anubis@gnu.org>.
$

You may find more help to port the right-way this software to Haiku here:
http://ports.haiku-files.org