PR/59351 compat_setjmp is busted

Apply the patch in the PR from Valery Ushakov (thanks) which restores
the restoration of r0, lr after the call to sigblock that was lost in
revision 1.3

Author: skrll

lib/libc/compat/arch/arm/gen/compat_setjmp.S

@@ -1,4 +1,4 @@
-/*	$NetBSD: compat_setjmp.S,v 1.5 2020/12/05 11:18:21 skrll Exp $	*/
+/*	$NetBSD: compat_setjmp.S,v 1.6 2026/03/18 18:23:53 skrll Exp $	*/
 
 /*
  * Copyright (c) 1997 Mark Brinicombe
@@ -46,12 +46,13 @@
  */
 
 ENTRY(setjmp)
-	/* Block all signals and retrieve the old signal mask */
+	/* Retrieve the old signal mask */
 	push	{r0, lr}
 	movs	r0, #0x00000000
 
 	bl	PLT_SYM(_C_LABEL(sigblock))
 	mov	r1, r0
+	pop	{r0, lr}
 
 	/* Store signal mask */
 	str	r1, [r0, #(_JB_SIGMASK * 4)]
@@ -83,7 +84,7 @@ ENTRY(setjmp)
 	stmia	r0, {r4-lr}
 #endif
 	movs	r0, #0
-	pop	{r3, pc}
+	RET
 END(setjmp)
 
 ENTRY(longjmp)