When multiple BSPs of the same arch are built in a build directory,
the differences in GL providers such as emgd-driver and mesa causes
rebuild of large set of recipes, as they collide on each other's space
for multiple BSPs. Although this does not impact correctness, it
impacts build performance negatively.

 Richard had an idea of providing separate PACKAGE_DIR to the
colliding recipes to avoid the build area collision. And this approach
significantly reduces the negative impact on the build performance.

Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>