duplicate generic bits/msg.h for each arch using it, in prep to change

arch/arm/bits/msg.h

+struct msqid_ds {
+	struct ipc_perm msg_perm;
+	time_t msg_stime;
+	int __unused1;
+	time_t msg_rtime;
+	int __unused2;
+	time_t msg_ctime;
+	int __unused3;
+	unsigned long msg_cbytes;
+	msgqnum_t msg_qnum;
+	msglen_t msg_qbytes;
+	pid_t msg_lspid;
+	pid_t msg_lrpid;
+	unsigned long __unused[2];
+};

arch/i386/bits/msg.h

+struct msqid_ds {
+	struct ipc_perm msg_perm;
+	time_t msg_stime;
+	int __unused1;
+	time_t msg_rtime;
+	int __unused2;
+	time_t msg_ctime;
+	int __unused3;
+	unsigned long msg_cbytes;
+	msgqnum_t msg_qnum;
+	msglen_t msg_qbytes;
+	pid_t msg_lspid;
+	pid_t msg_lrpid;
+	unsigned long __unused[2];
+};

arch/m68k/bits/msg.h

+struct msqid_ds {
+	struct ipc_perm msg_perm;
+	time_t msg_stime;
+	int __unused1;
+	time_t msg_rtime;
+	int __unused2;
+	time_t msg_ctime;
+	int __unused3;
+	unsigned long msg_cbytes;
+	msgqnum_t msg_qnum;
+	msglen_t msg_qbytes;
+	pid_t msg_lspid;
+	pid_t msg_lrpid;
+	unsigned long __unused[2];
+};

arch/microblaze/bits/msg.h

+struct msqid_ds {
+	struct ipc_perm msg_perm;
+	time_t msg_stime;
+	int __unused1;
+	time_t msg_rtime;
+	int __unused2;
+	time_t msg_ctime;
+	int __unused3;
+	unsigned long msg_cbytes;
+	msgqnum_t msg_qnum;
+	msglen_t msg_qbytes;
+	pid_t msg_lspid;
+	pid_t msg_lrpid;
+	unsigned long __unused[2];
+};

arch/sh/bits/msg.h

+struct msqid_ds {
+	struct ipc_perm msg_perm;
+	time_t msg_stime;
+	int __unused1;
+	time_t msg_rtime;
+	int __unused2;
+	time_t msg_ctime;
+	int __unused3;
+	unsigned long msg_cbytes;
+	msgqnum_t msg_qnum;
+	msglen_t msg_qbytes;
+	pid_t msg_lspid;
+	pid_t msg_lrpid;
+	unsigned long __unused[2];
+};