include/hw: add helpers for defining versioned machine types

include/hw: add helpers for defining versioned machine types

The various targets which define versioned machine types have
a bunch of obfuscated macro code for defining unique function
and variable names using string concatenation.

This adds a couple of helpers to improve the clarity of such
code macro.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20240620165742.1711389-2-berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>