Retire dual-bsd-gpl.LICENSE

[pombredanne]

This should be a rule detecting two licenses, not a license
https://github.com/nexB/scancode-toolkit/blob/5189fc19d9a1cf3a942ebaee8e49f133b764ece4/src/licensedcode/data/licenses/dual-bsd-gpl.LICENSE

[pombredanne]

this is now deprecated alright and has been replaced by RULEs and proper license expressions: "bsd-new OR gpl-2.0" is what you get now instead.