Follow open source license LGPL-2.1+

Follow open source license LGPL-2.1+

(1) From 2.33.92, the license has been LGPL-2.1+. The fillowing is part
    of NEWS file.

   What's new in at-spi2-atk 2.33.92:

   * License is now LGPL-2.1+.
   * Several test fixes (thanks to Samuel THibault).
   * Initialize desktop name/path early; needed since we now defer
     registration.

(2) And open source license verification tool found that the full text
   of the license was missing. So this patch adds the license file to
   package and it will be installed as below.

   ./usr/share/licenses/libatk-bridge-2_0-0/COPYING

Change-Id: I20f05be53b332f382c55c95e758482ad11640d15