Don't display bogus parameter for sigreturn syscall

* linux/*/syscallent.h: For those arches which use sys_sigreturn,
not printargs, to show [rt_]sigreturn syscall, change number of arguments
from 1 to 0: sys_sigreturn function doesn't use syscall parameters.
(I guess kernel doesn't actually _have_ any parameters for this syscall,
at least on these architectures). Do the same change for I386 and x86-64
even though they use printargs: I looked at kernel code and syscall
definitely doesn't have any parameters on these arches.
(I hesitate to change 1 to 0 params for arches I don't know -
it is remotely possible some of them do have a parameter for this syscall).

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/linux/mips/syscallent.h b/linux/mips/syscallent.h
index 5756fae..3382ffd 100644
--- a/linux/mips/syscallent.h
+++ b/linux/mips/syscallent.h
@@ -4121,7 +4121,7 @@
 	{ 1,	0,	sys_sysinfo,		"sysinfo"	}, /* 4116 */
 	{ 6,	0,	sys_ipc,		"ipc"		}, /* 4117 */
 	{ 1,	TD,	sys_fsync,		"fsync"		}, /* 4118 */
-	{ 1,	TS,	sys_sigreturn,		"sigreturn"	}, /* 4119 */
+	{ 0,	TS,	sys_sigreturn,		"sigreturn"	}, /* 4119 */
 	{ 5,	TP,	sys_clone,		"clone"		}, /* 4120 */
 	{ 2,	0,	sys_setdomainname,	"setdomainname"	}, /* 4121 */
 	{ 1,	0,	sys_uname,		"uname"		}, /* 4122 */