make arm setjmp/longjmp asm thumb2-compatible

sp cannot be used in the ldm/stm register set in thumb mode.

src/setjmp/arm/longjmp.s

@@ -8,7 +8,9 @@ longjmp:
 	mov ip,r0
 	movs r0,r1
 	moveq r0,#1
-	ldmia ip!, {v1,v2,v3,v4,v5,v6,sl,fp,sp,lr}
+	ldmia ip!, {v1,v2,v3,v4,v5,v6,sl,fp}
+	ldmia ip!, {r2,lr}
+	mov sp,r2
 
 	adr r1,1f
 	ldr r2,1f

src/setjmp/arm/setjmp.s

@@ -9,7 +9,9 @@ __setjmp:
 _setjmp:
 setjmp:
 	mov ip,r0
-	stmia ip!,{v1,v2,v3,v4,v5,v6,sl,fp,sp,lr}
+	stmia ip!,{v1,v2,v3,v4,v5,v6,sl,fp}
+	mov r2,sp
+	stmia ip!,{r2,lr}
 	mov r0,#0
 
 	adr r1,1f