license.py: Correct selection of licenses in is_included()

license.py: Correct selection of licenses in is_included()

When faced with multiple sets of licenses combined with | (OR), it was
possible for oe.license.is_included() to choose a set of licenses with
a blacklisted license and then report failure, even if choosing
another set of licenses would have resulted in a successful
result. This happened when the chosen set still contained more
whitelisted licenses than the other set.

This change makes sure a set with any blacklisted license is always
considered with a lower weight than a set with only whitelisted
licenses.

Example: Faced with the license string "GPL-3.0 & GPL-2.0 & LGPL-2.1 |
Proprietary" and with "GPL-3.0" being blacklisted, the old code would
report a failure since "GPL-3.0 & GPL-2.0 & LGPL-2.1" still contains
more whitelisted licenses than "Proprietary" does.

This change also adds a unit test for oe.license.is_included().

(From OE-Core rev: 312b4d6175e189852c0787ca2fe99b99ce92d1bd)

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>