This will prevent: 1) rendering problems (commands sent to the client in the wrong order)
2) sending commands for surfaces that haven't been created yet on the client side.

This used to be a callback for the vdi_port "data ready" interrupt,
which did indicate either data ready to read or data ready to write, but
this is no longer the case now that virtio-serial is used.

This seemingly simple fix prevents a race that needs to be fixed with
another patch, see freedesktop bz #29903

The vdi_port_write_timer_started flag was not being reset, which prevented
another vdi_port_write_timer_start from actually starting the timer. Fix
is to change order of lines. This happens in the callback of the timer, so
no chance of double timer set.

A side effect of the previous red_current_flush, which flushed all the surfaces, and was called on a new display channel connection, was
that red_handle_drawable_surfaces_client_synced sent the most updated surfaces images when needed. However, now, it should
explicitly call red_current_flush.
Moreover, since red_current_flush was called on a new display channel connection only if there was a primary surface,
if the connection of the display channel occurred at the moment of no primary surface, red_handle_drawable_surfaces_client_synced was buggy.

Update #define in server/spice.h in preparation for the 0.6.0 release.
We also got some new functions, thus we have to increate the shared
lib minor number for spice-server.

A bunch of configuration functions where never ported forward from
rhel-6 to upstream.  Add them so we can add qemu config options for
these settings.