ibus vulnerability

USN-4134-1 fixed a vulnerability in IBus. The update caused a regression in
some Qt applications and the fix was subsequently reverted in
USN-4134-2. The regression has since been resolved and so this update fixes
the original vulnerability.

We apologize for the inconvenience.

Original advisory details:

Simon McVittie discovered that IBus did not enforce appropriate access
controls on its private D-Bus socket. A local unprivileged user who
discovers the IBus socket address of another user could exploit this to
capture the key strokes of the other user.