sstate: Add a two character subdirectory to the sstate directory layout
Currently all sstate files are placed into one directory. This does not scale and
causes a variety of filesystem issues. This patch adds a two character subdirectory
to the layout (based on the first two characters of the hash) so that files
can be split into several directories.
This should help performance of sstate in most cases.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
