rpm: convert license to SPDX format

rpm: convert license to SPDX format

Note that with the introduction of SPDX, Fedora no longer wants
maintainers to do effective license analysis, hence we now list
all the licenses that are applicable to the binary package
contents

  https://docs.fedoraproject.org/en-US/legal/license-field/#_no_effective_license_analysis

Note, we can still omit licenses that are only applicable to
the build system.

Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>