Some parts of a keg's tree are not subject to the cleaner, and sometimes
we still want to remove things in directories marked skip_clean; this
allows us that freedom.
If 'lib' is marked skip_clean, we still want to avoid linking the
charset.alias file into the top of the tree. The same needs to be done
for the locale.alias file in share/locale.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>