findpaths: Fix subpath support

Due to an incorrect a specified subpath would be ignored.
findpaths: Add option -R/--reverse

It causes the paths to be printed in reverse order.
/etc/profile: Also source profile.d/*.sh files in data dirs

This allows packages to place files in data/profile.d to manipulate
the shell environment. They could already use settings/etc/profile.d,
but since there's no point in editing those files in most cases, placing
them there nonetheless doesn't make much sense.