parasite: use a correct original registers

Use original registers, which belong to the executing thread.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

parasite-syscall.c

@@ -133,7 +133,7 @@ retry_signal:
 		 * and retry.
 		 */
 
-		if (ptrace(PTRACE_SETREGS, pid, NULL, &ctl->threads[0].regs_orig)) {
+		if (ptrace(PTRACE_SETREGS, pid, NULL, &regs_orig)) {
 			pr_perror("Can't set registers (pid: %d)", pid);
 			goto err;
 		}