Disable Nanogui and build on precise.

Former-commit-id: 60db4b12aee217b49cbd795367374c80ff24a043

.travis.yml

@@ -1,6 +1,6 @@
 language: cpp
 sudo: false
-dist: trusty
+dist: precise
 matrix:
   include:
     - os: linux
@@ -20,7 +20,7 @@ matrix:
         - cd tutorial
         - mkdir build
         - cd build
-        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 ../
+        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DLIBIGL_WITH_NANOGUI=OFF -DCMAKE_CXX_COMPILER=g++-4.8 -DCMAKE_C_COMPILER=gcc-4.8 ../
         - make -j 2
       addons:
         apt:
@@ -63,5 +63,5 @@ matrix:
         - cd tutorial
         - mkdir build
         - cd build
-        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DLIBIGL_WITH_EMBREE=OFF ../
+        - cmake -DLIBIGL_USE_STATIC_LIBRARY=ON -DLIBIGL_WITH_NANOGUI=OFF -DLIBIGL_WITH_EMBREE=OFF ../
         - make -j 2