Expand to support ifmedia(4) types as found on BSD.

https://bugzilla.gnome.org/show_bug.cgi?id=652713

doc/reference/libgtop-sections.txt

@@ -167,6 +167,7 @@ glibtop_get_uptime_s
 <FILE>netlist</FILE>
 <TITLE>Net List</TITLE>
 GLIBTOP_NETLIST_NUMBER
+GLIBTOP_NETLIST_MEDIA_TYPE
 GLIBTOP_MAX_NETLIST
 glibtop_netlist
 glibtop_get_netlist

include/glibtop/netlist.h

@@ -26,8 +26,9 @@
 G_BEGIN_DECLS
 
 #define GLIBTOP_NETLIST_NUMBER		0
+#define GLIBTOP_NETLIST_MEDIA_TYPE	1
 
-#define GLIBTOP_MAX_NETLIST		1
+#define GLIBTOP_MAX_NETLIST		2
 
 typedef struct _glibtop_netlist	glibtop_netlist;
 
@@ -35,6 +36,7 @@ struct _glibtop_netlist
 {
 	guint64 flags;
 	guint32 number;
+	gchar *dev_type;
 };
 
 char** glibtop_get_netlist(glibtop_netlist *buf);