Fix atk-adaptor re-entry problem during register application.
Fix atk-adaptor re-entry problem during register application.

Bug #27626.

GNOME/at-spi2-core,Distrotech/at-spi2-atk,GNOME/at-spi2-core,Distrotech/at-spi2-atk,GNOME/at-spi2-core,GNOME/at-spi2-atk