Portability fixes from Mats Erik Andersson <debian@gisladisker.se>

It restores compilability and most functionality for

   GNU/Linux,
   GNU/kFreeBSD,
   FreeBSD,
   OpenBSD,
   OpenSolaris/NexentaCore.

addrs_ioctl.c

@@ -19,7 +19,7 @@
 #include <netinet/in.h>
 
 #if defined __FreeBSD__ || defined __OpenBSD__ || defined __APPLE__ \
-      || ( defined __GNUC__ && ! defined __linux__ )
+      || ( defined __GLIBC__ && ! defined __linux__ )
 #include <sys/param.h>
 #include <sys/sysctl.h>
 #include <net/if_dl.h>
@@ -81,7 +81,7 @@ get_addrs_ioctl(char *interface, char if_hw_addr[], struct in_addr *if_ip_addr,
   }
 #else
 #if defined __FreeBSD__ || defined __OpenBSD__ || defined __APPLE__ \
-      || ( defined __GNUC__ && ! defined __linux__ )
+      || ( defined __GLIBC__ && ! defined __linux__ )
   {
     int sysctlparam[6] = {CTL_NET, PF_ROUTE, 0, 0, NET_RT_IFLIST, 0};
     size_t needed = 0;

configure.in

@@ -355,7 +355,7 @@ oldLIBS=$LIBS
 for curseslib in ncursesw curses ncurses ; do
     LIBS="$oldLIBS -l$curseslib"
     AC_TRY_LINK([
-#include <curses.h>
+#include <$curseslib.h>
         ], [
         mvchgat(0, 0, 1, A_REVERSE, 0, NULL)
         ], [

dlcommon.c

@@ -25,6 +25,7 @@ typedef	unsigned long	ulong;
 #include	<sys/dlpi.h>
 #include	<sys/signal.h>
 #include	<stdio.h>
+#include	<stdlib.h>
 #include	<string.h>
 #include	"dlcommon.h"
 
@@ -462,7 +463,7 @@ char	*bufp;
 		err("dlphysaddrack:  short response ctl.len:  %d", ctl.len);
 }
 
-static void
+void
 sigalrm()
 {
 	(void) err("sigalrm:  TIMEOUT");

iftop.h

@@ -13,6 +13,16 @@
 #define RESOLUTION 2
 #define DUMP_RESOLUTION 300
 
+/* At least OpenBSD and NexentaCore do not
+ * define s6_addr32 for user land settings.
+ */
+#if !defined s6_addr32 && defined __sun__
+#	define s6_addr32 _S6_un._S6_u32
+#elif !defined s6_addr32 && \
+		( defined __OpenBSD__ || defined __FreeBSD__ )
+#	define s6_addr32 __u6_addr.__u6_addr32
+#endif	/* !defined s6_addr32 */
+
 typedef struct {
     long recv[HISTORY_LENGTH];
     long sent[HISTORY_LENGTH];

ui.c

@@ -6,7 +6,7 @@
 #include <sys/types.h>
 
 #include <ctype.h>
-#include <curses.h>
+#include <ncurses.h>
 #include <errno.h>
 #include <string.h>
 #include <math.h>