tests/xbps-create: fix the rejectfifo test.

It was using -a (alternatives) rather than -A (architecture)
so the test wasn't checking the exact error branch.

tests/xbps/xbps-create/basic_test.sh

@@ -175,7 +175,7 @@ reject_fifo_file_head() {
 reject_fifo_file_body() {
 	mkdir -p repo pkg_a
 	mkfifo pkg_a/fifo
-	xbps-create -a noarch -n foo-1.0_1 -s "foo pkg" pkg_a
+	xbps-create -A noarch -n foo-1.0_1 -s "foo pkg" pkg_a
 	atf_check_equal $? 1
 }