iptables-restore: fix segmentation fault with -tanything

Reference: Debian bug #458042

iptables-restore must not pass a table into do_command. It checks for
"-t arg" and "--table arg", but not "-targ". (On a related note,
using -targ does not work as expected).

This should fail gracefully, but crashes:

	iptables-restore <(echo -e '*filter\n-A INPUT -tx\nCOMMIT')

And this should use table "filter", or perhaps raise an error, but
instead sets the table to (literally) "-tfilter":

	iptables -tfilter -A INPUT

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/iptables-restore.c b/iptables-restore.c
index 4b199d9..dcbed14 100644
--- a/iptables-restore.c
+++ b/iptables-restore.c
@@ -412,7 +412,7 @@
 					param_buffer[param_len] = '\0';
 
 					/* check if table name specified */
-					if (!strncmp(param_buffer, "-t", 3)
+					if (!strncmp(param_buffer, "-t", 2)
 					    || !strncmp(param_buffer, "--table", 8)) {
 						exit_error(PARAMETER_PROBLEM,
 						   "Line %u seems to have a "