Separate notion of _FLOOD constant from the flags stored in the Flooding struct

This adds a FLOOD_FLAG() macro to convert a _FLOOD constant to the appropriate flag.  For now this just
casts the argument to unsigned int.

Rename Flooding.type to Flooding.flags and change it to unsigned int, to reflect that it's a bitfield of
flags for multiple flooding types.

include/struct.h

@@ -1012,7 +1012,7 @@ typedef struct	flood_stru
 	char	*name;
 	char	*host;
 	char	*channel;
-	int	type;
+	unsigned flags;
 	char	flood;
 	unsigned long	cnt;
 	struct timeval	start;