Adapt previous; put #ifdef SVS around the declaration directly.

sys/arch/amd64/amd64/locore.S

@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.S,v 1.154 2018/02/22 14:08:48 martin Exp $	*/
+/*	$NetBSD: locore.S,v 1.155 2018/02/22 14:57:11 maxv Exp $	*/
 
 /*
  * Copyright-o-rama!
@@ -1378,7 +1378,6 @@ IDTVEC(\name)
 
 #define SP(x,reg)	(x)-(TF_SS+8)(reg)
 
-#ifdef SVS
 	.if	\is_svs
 		movq	%rax,SVS_UTLS+UTLS_SCRATCH
 		movq	SVS_UTLS+UTLS_RSP0,%rax
@@ -1393,7 +1392,6 @@ IDTVEC(\name)
 
 		movq	SVS_UTLS+UTLS_SCRATCH,%rax
 	.else
-#endif
 		movq	%r15,CPUVAR(SCRATCH)
 		movq	CPUVAR(CURLWP),%r15
 		movq	L_PCB(%r15),%r15
@@ -1408,9 +1406,7 @@ IDTVEC(\name)
 		leaq	SP(0,%r15),%rsp			/* %rsp now valid after frame */
 
 		movq	CPUVAR(SCRATCH),%r15
-#ifdef SVS
 	.endif
-#endif
 
 #undef SP
 
@@ -1440,7 +1436,9 @@ SYSCALL_ENTRY	syscall,is_svs=0
 
 	TEXT_USER_BEGIN
 
+#ifdef SVS
 SYSCALL_ENTRY	syscall_svs,is_svs=1
+#endif
 
 IDTVEC(syscall32)
 	sysret		/* go away please */