local.conf.sample: Add automatic defaults for BB_NUMBER_THREADS and PARALLEL_MAKE
Its rather sad that people don't appear to read local.conf and then complain
about slow builds when they're just using a single thread. Most systems have
more than one core now so we might as well use a more automatic default
for these values. This may lead to better experiences for new users.
[YOCTO #2528]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
