include/hw/boards: cope with dev/rc versions in deprecation checks

include/hw/boards: cope with dev/rc versions in deprecation checks

When VERSION is set to a development snapshot (micro >= 50), or a release
candidate (micro >= 90) we have an off-by-1 in determining deprecation
and deletion thresholds for versioned machine types. In such cases we need
to use the next major/minor version in threshold checks.

This adapts the deprecation macros to do "next version" prediction when
seeing a dev/rc version number.

This ensures users of release candidates get an accurate view of machines
that will be deprecated/deleted in the final release.

This requires hardcoding our current release policy of 3 releases per
year, with a major bump at the start of each year, and that dev/rc
versions have micro >= 50.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>