Convert license to SPDX format
This new expression is a result of
* Running 'licensecheck -r .' across the QEMU code base
* Ignoring results not applicable to Fedora platform
* Ignoring stuff only used in test cases
* Adding missing logo license
* Considering upstream default license for non-annotated files
Note license expression simplication is no longer to be performed in
Fedora, so the new expression is unavoidably much larger than before.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>