oe-init-build-env: unset BBSERVER
If BBSERVER is set, we should unset it before proceeding. Its assumed the
user will have unloaded the server from memory should they have wished
to do so.
(From OE-Core rev: 5cc4d315709de195bfb0655c2f00ae2267bfa4c6)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>