bitbake-worker: ensure BUILDNAME is available during execution

BUILDNAME is set from cooker by default, so since the worker split it
will not be set when executing functions. In OpenEmbedded this results
in /etc/version (which is populated from BUILDNAME) not having any
content. Pass this variable value through to the worker explicitly to
fix the issue.

Fixes [YOCTO #4818].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
hob: remove PACKAGE_INSTALL variable setting from hob

Before saving the packages for a custom images in a .bb file,
the packages were saved in bitbake memory. Now all the variables
are saved in conf file, so saving PACKAGE_INSTALL is not needed anymore.
Moved were LINGUAS_INSTALL is set, because both conditions are for testing
if a custom image is saved.

[YOCTO #5101]
Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>