iproute2: man page and /bin/ip disagree on del vs delete

Reported by Robert Henney:
> the 'ip' man page does not mention the command "del" at all but does
> claim, "As a rule, it is possible to add, delete and show (or list ) objects".
> however, 'ip' does not always recognize "delete" as a commend.
>
> robh@debian:~$ ip tunnel delete
> Command "delete" is unknown, try "ip tunnel help".

Lets use "delete" in all calls to matches() for consistency. This will
make both "del" and "delete" work everywhere.
Signed-off-by: Andreas Henriksson <andreas@fatal.se>

ip/ip6tunnel.c

@@ -408,7 +408,7 @@ int do_ip6tunnel(int argc, char **argv)
 			return do_add(SIOCADDTUNNEL, argc - 1, argv + 1);
 		if (matches(*argv, "change") == 0)
 			return do_add(SIOCCHGTUNNEL, argc - 1, argv + 1);
-		if (matches(*argv, "del") == 0)
+		if (matches(*argv, "delete") == 0)
 			return do_del(argc - 1, argv + 1);
 		if (matches(*argv, "show") == 0 ||
 		    matches(*argv, "lst") == 0 ||

ip/ipl2tp.c

@@ -795,7 +795,7 @@ int do_ipl2tp(int argc, char **argv)
 
 	if (matches(*argv, "add") == 0)
 		return do_add(argc-1, argv+1);
-	if (matches(*argv, "del") == 0)
+	if (matches(*argv, "delete") == 0)
 		return do_del(argc-1, argv+1);
 	if (matches(*argv, "show") == 0 ||
 	    matches(*argv, "lst") == 0 ||

ip/iptunnel.c

@@ -620,7 +620,7 @@ int do_iptunnel(int argc, char **argv)
 			return do_add(SIOCADDTUNNEL, argc-1, argv+1);
 		if (matches(*argv, "change") == 0)
 			return do_add(SIOCCHGTUNNEL, argc-1, argv+1);
-		if (matches(*argv, "del") == 0)
+		if (matches(*argv, "delete") == 0)
 			return do_del(argc-1, argv+1);
 		if (matches(*argv, "show") == 0 ||
 		    matches(*argv, "lst") == 0 ||

ip/iptuntap.c

@@ -307,7 +307,7 @@ int do_iptuntap(int argc, char **argv)
 	if (argc > 0) {
 		if (matches(*argv, "add") == 0)
 			return do_add(argc-1, argv+1);
-		if (matches(*argv, "del") == 0)
+		if (matches(*argv, "delete") == 0)
 			return do_del(argc-1, argv+1);
 		if (matches(*argv, "show") == 0 ||
                     matches(*argv, "lst") == 0 ||