This clarifies that the majority of this package is LGPLv2+. Copyright
blurbs that pointed to QEMU's "COPYING" file are amended to point to
this repository's "LICENSE" file instead.

The only file that is not already licensed as LGPLv2+ is legacy.py,
which is GPLv2 only. Amend the copyright blurb there to point to
LICENSE_GPL2, which is a copy of qemu.git's COPYING file.

legacy.py is scheduled for removal, at which point the license of this
library will become exclusively LGPLv2+. As the package currently
contains a mixture of LGPLv2+ and GPLv2 code, the trove classifiers will
reflect this mixture until such time as the remaining GPLv2 code is
removed.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>