poky-init-build-env: unset BBPATH

When using OpenEmbedded and Yocto I had it previously set to OE and
this made bitbake to get confused. This was difficult to figure out
and then it seems safer and cleaner if the script unset it to avoid
this confusing behaviour.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

poky-init-build-env

@@ -38,6 +38,7 @@ else
    . $OEROOT/scripts/poky-env-internal
    $OEROOT/scripts/poky-setup-builddir
    unset OEROOT
+   unset BBPATH
    [ -n "$BUILDDIR" ] && cd $BUILDDIR
 fi