Add gcc_struct to all packed structures when compiling with mingw.

Just "packed" doesn't always pack the way we expect.

grub-core/net/arp.c

@@ -43,7 +43,7 @@ struct arphdr {
   grub_uint8_t hln;
   grub_uint8_t pln;
   grub_uint16_t op;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 static int have_pending;
 static grub_uint32_t pending_req;

grub-core/net/dns.c

@@ -86,7 +86,7 @@ struct dns_header
   grub_uint16_t ancount;
   grub_uint16_t nscount;
   grub_uint16_t arcount;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 enum
   {

grub-core/net/drivers/i386/pc/pxe.c

@@ -45,7 +45,7 @@ struct grub_pxe_undi_open
   grub_uint16_t pkt_filter;
   grub_uint16_t mcast_count;
   grub_uint8_t mcast[8][6];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct grub_pxe_undi_info
 {
@@ -60,7 +60,7 @@ struct grub_pxe_undi_info
   grub_uint32_t romaddr;
   grub_uint16_t rxbufct;
   grub_uint16_t txbufct;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 
 struct grub_pxe_undi_isr
@@ -73,7 +73,7 @@ struct grub_pxe_undi_isr
   grub_uint32_t buffer;
   grub_uint8_t prot_type;
   grub_uint8_t pkt_type;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 enum
   {
@@ -104,7 +104,7 @@ struct grub_pxe_undi_transmit
   grub_uint32_t dest;
   grub_uint32_t tbd;
   grub_uint32_t reserved[2];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct grub_pxe_undi_tbd
 {
@@ -118,7 +118,7 @@ struct grub_pxe_undi_tbd
     grub_uint16_t len;
     grub_uint32_t ptr;
   } blocks[8];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct grub_pxe_bangpxe *grub_pxe_pxenv;
 static grub_uint32_t pxe_rm_entry = 0;

grub-core/net/ethernet.c

@@ -33,20 +33,20 @@ struct etherhdr
   grub_uint8_t dst[6];
   grub_uint8_t src[6];
   grub_uint16_t type;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct llchdr
 {
   grub_uint8_t dsap;
   grub_uint8_t ssap;
   grub_uint8_t ctrl;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct snaphdr
 {
   grub_uint8_t oui[3]; 
   grub_uint16_t type;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 grub_err_t
 send_ethernet_packet (struct grub_net_network_level_interface *inf,

grub-core/net/icmp.c

@@ -25,13 +25,13 @@ struct icmp_header
   grub_uint8_t type;
   grub_uint8_t code;
   grub_uint16_t checksum;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct ping_header
 {
   grub_uint16_t id;
   grub_uint16_t seq;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 enum
   {

grub-core/net/icmp6.c

@@ -25,13 +25,13 @@ struct icmp_header
   grub_uint8_t type;
   grub_uint8_t code;
   grub_uint16_t checksum;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct ping_header
 {
   grub_uint16_t id;
   grub_uint16_t seq;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct router_adv
 {
@@ -41,13 +41,13 @@ struct router_adv
   grub_uint32_t reachable_time;
   grub_uint32_t retrans_timer;
   grub_uint8_t options[0];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct option_header
 {
   grub_uint8_t type;
   grub_uint8_t len;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct prefix_option
 {
@@ -58,19 +58,19 @@ struct prefix_option
   grub_uint32_t preferred_lifetime;
   grub_uint32_t reserved;
   grub_uint64_t prefix[2];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct neighbour_solicit
 {
   grub_uint32_t reserved;
   grub_uint64_t target[2];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct neighbour_advertise
 {
   grub_uint32_t flags;
   grub_uint64_t target[2];
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 enum
   {

grub-core/net/ip.c

@@ -38,7 +38,7 @@ struct iphdr {
   grub_uint16_t chksum;
   grub_uint32_t src;
   grub_uint32_t dest;
-} __attribute__ ((packed)) ;
+} GRUB_PACKED ;
 
 enum
 {
@@ -56,7 +56,7 @@ struct ip6hdr {
   grub_uint8_t ttl;
   ip6addr src;
   ip6addr dest;
-} __attribute__ ((packed)) ;
+} GRUB_PACKED ;
 
 static int
 cmp (const void *a__, const void *b__)

grub-core/net/tcp.c

@@ -104,7 +104,7 @@ struct tcphdr
   grub_uint16_t window;
   grub_uint16_t checksum;
   grub_uint16_t urgent;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct tcp_pseudohdr
 {
@@ -113,7 +113,7 @@ struct tcp_pseudohdr
   grub_uint8_t zero;
   grub_uint8_t proto;
   grub_uint16_t tcp_length;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 struct tcp6_pseudohdr
 {
@@ -122,7 +122,7 @@ struct tcp6_pseudohdr
   grub_uint32_t tcp_length;
   grub_uint8_t zero[3];
   grub_uint8_t proto;
-} __attribute__ ((packed));
+} GRUB_PACKED;
 
 static struct grub_net_tcp_socket *tcp_sockets;
 static struct grub_net_tcp_listen *tcp_listens;

grub-core/net/tftp.c

@@ -94,7 +94,7 @@ struct tftphdr {
       grub_int8_t data[TFTP_DEFAULTSIZE_PACKET+2];
     } oack;
   } u;
-} __attribute__ ((packed)) ;
+} GRUB_PACKED ;
 
 
 typedef struct tftp_data