libbsd-dev is needed in CFLAGS and LDFLAGS to build on Debian 12

[nroach44]

Hi, thanks for your project!

When trying to install this on a reasonably clean Debian 12 install, I get the following error:

retronet.c: In function ‘rn_req_tcp_open’:
retronet.c:1753:9: error: implicit declaration of function ‘strlcpy’; did you mean ‘strncpy’? [-Werror=implicit-function-declaration]
 1753 |         strlcpy((char *)le->details.hostname,
      |         ^~~~~~~
      |         strncpy
cc1: all warnings being treated as errors
make[2]: *** [Makefile:610: nabud-retronet.o] Error 1

I also got this after "fixing" the above:

/usr/bin/ld: nabud-main.o: in function `main':
main.c:(.text+0x117a): undefined reference to `bsd_getopt'
/usr/bin/ld: nabud-retronet.o: in function `rn_req_tcp_open':
retronet.c:(.text+0x3c8b): undefined reference to `strlcpy'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:466: nabud] Error 1

I ended up fixing it all by installing libbsd-dev, and running export CFLAGS="-DLIBBSD_OVERLAY -I/usr/include/bsd" and export LDFLAGS="-lbsd"

I just wanted to note it here as it's both missed by the configure script and I couldn't see it documented anywhere.