As BB_NUMBER_THREADS is already whitelisted, it is consistent to
also allow PARALLEL_MAKE to be overridden via the environment. This
also simplifies performance testing where multiple combinations of
those two variables are a natural thing to do.
(From OE-Core rev: 8a89a2e641fd5fa97a7d6977f55d10790ee13d58)
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
