Update at-spi2-core to 2.25.91

This has several fixes which aren't in the "stable" 2.24.1

What's new in at-spi2-core 2.25.91:

* Meson builds should now be usable.

What's new in at-spi2-core 2.25.90:

* Fix a couple of introspection issues (bgo#784481).
* atspi_get_a11_bus: don't leak the DBusConnection.
* Meson fixes.

What's new in at-spi2-core 2.25.4:

* Fix gir generation with autotools (bgo#783994).

What's new in at-spi2-core 2.25.3:

* Fix -Wmisleading-indentation warnings.
* Fix memory leak of at-spi-bus-launcher.
* Add error-message, error-for, details, and details-for relation types.
* Poll direct dbus connections in the main loop--fixes processes
  being marked hung and the hung flag never being removed.
* Add Meson build system (thanks to Emmanuele Bassi).
* Various build fixes (thanks to Emmanuele Bassi).

What's new in at-spi2-core 2.25.2:

* attempt to fix an occasional crash when an application disappears
  (bgo#767074).
* Add some missing roles to correspond with atk (description list,
  description term, description value, and footnote).

What's new in at-spi2-core 2.25.1:

* atspi_table_cell_get_position: don't crash on error.

What's new in at-spi2-core 2.23.92:

* Table cell API fixes (bgo#779835).

What's new in at-spi2-core 2.23.90:

* Fix an occasional crash when an application is closed (bgo#767074).

What's new in at-spi2-core 2.23.4:

* Don't pull in X headers if x11 is disabled (bgo#773710).
* at-spi-bus-launcher: session management fixes (bgo#774441).
* events: add recently added page changed event (bgo#719898).
* roles: EXTENDED roles are deprecated (bgo#W720123).

(prlw1)