tests: add alarm.test

* tests/alarm.c: New file.
* tests/alarm.test: New test.
* tests/.gitignore: Add alarm.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(TESTS): Add alarm.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index ef187d9..b7da7dd 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -8,6 +8,7 @@
 _newselect
 adjtimex
 aio
+alarm
 attach-f-p
 attach-p-cmd-cmd
 attach-p-cmd-p