Declare syscall parsers using SYS_FUNC macro

Introduce SYS_FUNC macro to declare and define all syscall parsers.

* Makefile.am (BUILT_SOURCES, CLEANFILES): Add sys_func.h.
(sys_func.h): New rule.
* defs.h (SYS_FUNC_NAME, SYS_FUNC): New macros.
* linux/syscall.h: Include "sys_func.h".
[NEED_UID16_PARSERS]: Use SYS_FUNC to declare uid16 syscall parsers.
Remove other declarations.
* linux/alpha/syscallent.h (160, 161): Add sys_ prefix to osf_statfs
and osf_fstatfs syscall parsers.
* *.c: Use SYS_FUNC to define syscall parsers.
diff --git a/link.c b/link.c
index 2f5298f..74ff514 100644
--- a/link.c
+++ b/link.c
@@ -20,8 +20,7 @@
 
 #include "xlat/at_flags.h"
 
-int
-sys_link(struct tcb *tcp)
+SYS_FUNC(link)
 {
 	if (entering(tcp)) {
 		printpath(tcp, tcp->u_arg[0]);
@@ -31,8 +30,7 @@
 	return 0;
 }
 
-int
-sys_linkat(struct tcb *tcp)
+SYS_FUNC(linkat)
 {
 	if (entering(tcp)) {
 		print_dirfd(tcp, tcp->u_arg[0]);
@@ -46,8 +44,7 @@
 	return 0;
 }
 
-int
-sys_unlinkat(struct tcb *tcp)
+SYS_FUNC(unlinkat)
 {
 	if (entering(tcp)) {
 		print_dirfd(tcp, tcp->u_arg[0]);
@@ -58,8 +55,7 @@
 	return 0;
 }
 
-int
-sys_symlinkat(struct tcb *tcp)
+SYS_FUNC(symlinkat)
 {
 	if (entering(tcp)) {
 		printpath(tcp, tcp->u_arg[0]);