Fixed NetFlow v9 flow data misalignment

NetFlow v9 flow data has to be aligned on a 32 bit boundary by inserting padding at the end of the flowset.
In pfSense 2.0, every even flow in a NetFlow v9 flowset is shifted by two bytes. Those extra bytes are added by the compiler, which aligns NF9_IPV4_DATA on a 4-byte boundary (42 bytes -> 44 bytes)

Adding "packed" attribute fixed this issue.
Verified using Wireshark and Plixer Scrutinizer.

pfPorts/pfflowd-0.8/files/nf9.h

@@ -1,4 +1,3 @@
-
 #ifndef _NF9_H
 # define _NF9_H
 
@@ -184,7 +183,7 @@ struct NF9_IPV4_DATA
    u_int16_t src_port, dst_port;
    u_int16_t src_index, dst_index;
    u_int8_t protocol, direction;
-};
+} __attribute__ ((packed));
 
 /*
  * Data Record for Internet Protocol version 6 (IPv6)
@@ -200,7 +199,7 @@ struct NF9_IPV6_DATA
    u_int16_t src_index, dst_index;
    u_int8_t protocol, direction;
 
-};
+} __attribute__ ((packed));
 
 /*Ethernet MTU is 1500, IPv6 header is 40 octets(no options) ,UDP header is 8 octets*/