The post-build custom command to embed Vista elevation manifest into
mariadb-upgrade-wizard.exe seems to do
something nasty to the executable, perhaps it removes and recreates it.

Thus the previously created hardlink mysql_upgrade_wizard is not marked
to require elevation.

Solved by using MANIFESTUAC linker flag, rather than invoke mt.exe.
This avoids an extra post-build step that modifies mariadb-upgrade-wizard.exe