fix broken sigsetjmp on x86_64

src/signal/x86_64/sigsetjmp.s

@@ -1,11 +1,13 @@
 /* Copyright 2011 Nicholas J. Kain, licensed GNU LGPL 2.1 or later */
 .global sigsetjmp
 sigsetjmp:
-	test %rsi,%rsi
-	jz 1f              /* if save == 0, just goto setjmp */
-	movq %rsi,64(%rdi) /* move save -> jmp_buf[8] */
-	addq $72,%rdi      /* add sizeof(jmp_buf) to rdi */
-	movl $0,%esi       /* arg2 = 0 */
-	movl $2,%edx       /* arg3 = 2 */
-	call sigprocmask   /* sigprocmask(jmp_buf, 0, 2) */
+	andl %esi,%esi
+	movq %rsi,64(%rdi)
+	jz 1f
+	pushq %rdi
+	leaq 72(%rdi),%rsi
+	xorl %edx,%edx
+	movl $2,%edi
+	call sigprocmask
+	popq %rdi
 1:	jmp setjmp