travis: install lua-posix and correct the symlink

Author: knixeur

.travis.yml

@@ -5,7 +5,9 @@ compiler:
 env:
   - 
   - USE_XFT=0
-before_install: sudo apt-get install lua5.2 liblua5.2-dev gettext libxft-dev libxinerama-dev libxrandr-dev libreadline-dev
+before_install:
+  - sudo apt-get install lua5.2 liblua5.2-dev gettext libxft-dev libxinerama-dev libxrandr-dev libreadline-dev lua-posix
+  - sudo ln -sf /usr/lib/x86_64-linux-gnu/lua/5.2/posix_c.so /usr/lib/x86_64-linux-gnu/lua/5.2/posix.so
 script:
   - make
   - make test