Save $? before case statement.

In some shells (FreeBSD 9, ash) the case statement resets $?, so save
for later testing.

regress/key-options.sh

@@ -101,9 +101,10 @@ check_valid_before() {
 	sed "s/.*/$opts &/" $origkeys >$authkeys
 	verbose "key option expiry-time $which"
 	${SSH} -q -F $OBJ/ssh_proxy somehost true
+	r=$?
 	case "$expect" in
-	fail)	test $? -eq 0 && fail "key option succeeded $which" ;;
-	pass)	test $? -ne 0 && fail "key option failed $which" ;;
+	fail)	test $r -eq 0 && fail "key option succeeded $which" ;;
+	pass)	test $r -ne 0 && fail "key option failed $which" ;;
 	*)	fatal "unknown expectation $expect" ;;
 	esac
 }