add missing packages to bionic to allow mex build

Author: petercorke

.travis.yml

@@ -18,6 +18,7 @@ before_install:
 - mkdir lib
 - git clone --depth 50 https://github.com/petercorke/toolbox-common-matlab lib/common
 - git clone --depth 50 https://github.com/petercorke/spatial-math lib/spatial-math
+- sudo apt-get -y install libatk1.0-0 libxcursor1
 
 install:
  # install help2doc converter