Fixed appPidLocation check according to bug 20062 (PEAR)

System_Daemon requires that pidfiles live in their own directories, like `/var/run/appName/pidfile` instead of `/var/run/appName.pid`. This is conform to the policies of most Linux distributions about `/var/run/`.

However, the existing check failed to allow locations like `/dir/appName/pidfile` or `./appName/pidfile` as it was required that the path component of `appPidLocation` requires at least three nested directories like `/var/run/appName/..`

This commit fixes this.

A further improvement might be to perform the check only if the pidfile should being placed in `/var/run/` in order to allow `./pidfile` for example.