Look for both name and if_<name> strings in module metadata. Pseudo-devices

like tun are naming their modules using the 'if_; prefix and previous version of
the code failed to detect their presence in the kernel, resulting in the same
module being loaded twice.

sbin/ifconfig/ifconfig.c

@@ -1849,7 +1849,8 @@ ifmaybeload(char *name)
 				cp = mstat.name;
 			}
 			/* already loaded? */
-			if (!strncmp(name, cp, strlen(cp)))
+			if (strncmp(name, cp, strlen(cp)) == 0 ||
+			    strncmp(ifkind, cp, strlen(cp)) == 0)
 				return;
 		}
 	}