Implement decoding of splice, tee and vmsplice(2) syscalls

* io.c (print_loff_t): New function.
(sys_sendfile64): Use it.
(splice_flags): New xlat structure.
(sys_tee, sys_splice, sys_vmsplice): New functions.
* linux/syscall.h (sys_tee, sys_splice, sys_vmsplice): Declare them.
* linux/*/syscallent.h: Use them.
diff --git a/linux/avr32/syscallent.h b/linux/avr32/syscallent.h
index 11742c1..d8801a6 100644
--- a/linux/avr32/syscallent.h
+++ b/linux/avr32/syscallent.h
@@ -288,10 +288,10 @@
 	{ 1,	TD,	sys_unshare,		"unshare"	}, /* 258 */
 	{ 2,	0,	printargs,		"set_robust_list" }, /* 259 */
 	{ 3,	0,	printargs,		"get_robust_list" }, /* 260 */
-	{ 6,	TD,	printargs,		"splice"	}, /* 261 */
+	{ 6,	TD,	sys_splice,		"splice"	}, /* 261 */
 	{ 4,	TD,	printargs,		"sync_file_range" }, /* 262 */
-	{ 4,	TD,	printargs,		"tee"		}, /* 263 */
-	{ 4,	TD,	printargs,		"vmsplice"	}, /* 264 */
+	{ 4,	TD,	sys_tee,		"tee"		}, /* 263 */
+	{ 4,	TD,	sys_vmsplice,		"vmsplice"	}, /* 264 */
 	{ 5,	TD,	sys_epoll_pwait,	"epoll_pwait"	}, /* 265 */
 	{ 4,	TI,	sys_msgget,		"msgget"	}, /* 266 */
 	{ 4,	TI,	sys_msgsnd,		"msgsnd"	}, /* 267 */