net-mgmt/ipcad: touchup and build fixes

 - fix wrong test(1) option in bpf configure test
   preventing configuration to succeed when no bpf(4)
   device is present on the system
 - add a missing include to avoid undefined behaviour
   through homegrown artisanal offsetof(3) macro
 - set LICENSE

PR:		265512
Approved by:	vlm@lionet.info (maintainer timeout)

net-mgmt/ipcad/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	ipcad
 PORTVERSION=	3.7.3
-PORTREVISION=	2
+PORTREVISION=	3
 CATEGORIES=	net-mgmt
 MASTER_SITES=	SF/${PORTNAME}/${PORTNAME}/${PORTNAME}-${PORTVERSION} \
 		http://ipcad.sourceforge.net/ \
@@ -10,6 +10,9 @@ MAINTAINER=	vlm@lionet.info
 COMMENT=	IP accounting daemon with Cisco-like RSH and NetFlow export
 WWW=		http://ipcad.sourceforge.net/
 
+LICENSE=	BSD2CLAUSE
+LICENSE_FILE=	${WRKSRC}/COPYING
+
 USE_RC_SUBR=	ipcad
 SUB_FILES=	pkg-message
 

net-mgmt/ipcad/files/patch-configure

@@ -0,0 +1,22 @@
+--- configure.orig	2022-07-30 04:13:00 UTC
++++ configure
+@@ -5797,15 +5797,15 @@ if test ! -z "$with_psrc" ; then
+ 	PSRC="$withval"
+ elif test -c /dev/bpf0 ; then
+ 	PSRC=bpf
+-elif test -a /usr/include/pcap.h; then
++elif test -f /usr/include/pcap.h; then
+ 	PSRC=pcap
+-elif test -a /usr/include/pcap/pcap.h; then
++elif test -f /usr/include/pcap/pcap.h; then
+ 	PSRC=pcap
+ 	CFLAGS="$CFLAGS -I/usr/include/pcap"
+ 	CPPFLAGS="$CPPFLAGS -I/usr/include/pcap"
+-elif test -a ${ac_default_prefix}/include/pcap.h; then
++elif test -f ${ac_default_prefix}/include/pcap.h; then
+ 	PSRC=pcap
+-elif test -a ${ac_default_prefix}/include/pcap/pcap.h; then
++elif test -f ${ac_default_prefix}/include/pcap/pcap.h; then
+ 	CFLAGS="$CFLAGS -I${ac_default_prefix}/include/pcap"
+ 	CPPFLAGS="$CPPFLAGS -I${ac_default_prefix}/include/pcap"
+ 	PSRC=pcap

net-mgmt/ipcad/files/patch-headers.h

@@ -0,0 +1,10 @@
+--- headers.h.orig	2022-07-30 04:07:13 UTC
++++ headers.h
+@@ -32,6 +32,7 @@
+ #define	__need_sig_atomic_t	1
+ #endif
+
++#include <stddef.h>
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <string.h>