Fixes [YOCTO #9843]
The variable description was very brief. These changes added some
substance to the description and how the OpenEmbedded build system
uses the variable.
(From yocto-docs rev: cc9117d4e16c56dd54f81804fda94561e61d91a7)
Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>