_atspi_dbus_set_interfaces: Fix memory leak when called with invalid signature
_atspi_dbus_set_interfaces: Fix memory leak when called with invalid signature

    Fixes https://gitlab.gnome.org/GNOME/at-spi2-core/issues/24

GNOME/at-spi2-core,GNOME/at-spi2-core,GNOME/at-spi2-core