BB_PRESERVE_ENV wasn't working since data.inheritFromOS wasn't getting a
correct list of keys to import into the data store. This fixes
things so it does add all environment variables into the data store
when BB_PRESERVE_ENV is used.
(Bitbake rev: 843e9339c5ee3c99657a40a0e2c7dbd777b6ef06)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>