Log Message:
ardour: update to 8.10.0.

Fixes build.

Ardour 8.10 is now available for Linux, Windows and macOS. As with
the last several releases, 8.9 turned out to have at least a couple
of new major issues that required a hot-fix. We believe that we
have corrected issues with performance caused by scheduling of disk
input/output threads (these problems tended to be system dependent,
but were very real on systems where they occured).  Importing SMF
(MIDI) via drag-n-drop now uses the file name once again.
Content-slipping a region correctly causes an update of the playback
buffers so you can hear the result as expected.

In addition to those hot-fixes, 8.10 sees small updates to all our
non-default color themes, a new MIDI binding map for the M-Audio
Axiom 49 MkII and a new Lua script to duplicate regions on the
grid.