lib/oe/package: fix LOCALE_PATHS scan to create locale packages

lib/oe/package: fix LOCALE_PATHS scan to create locale packages

split_locales() must only check subdirectories in paths added to
LOCALE_PATHS to avoid creating weird packages based on filenames also
present in paths.

Without such a filter, cups recipe adding ${datadir}/cups/templates to
LOCALE_PATHS creates the following incorrect packages:
- cups-locale-add-class.tmpl
- cups-locale-add-printer.tmpl
- cups-locale-admin.tmpl

Signed-off-by: Jonathan GUILLOT <jonathan@joggee.fr>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>