[NET] rules: Add support to invert selectors

Introduces a new flag FIB_RULE_INVERT causing rules to apply
if the specified selector doesn't match.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/fib_rules.h b/include/linux/fib_rules.h
index adcdfbd..8270aac 100644
--- a/include/linux/fib_rules.h
+++ b/include/linux/fib_rules.h
@@ -6,6 +6,7 @@
 
 /* rule is permanent, and cannot be deleted */
 #define FIB_RULE_PERMANENT	1
+#define FIB_RULE_INVERT		2
 
 struct fib_rule_hdr
 {