Travis: Build on both g++ and clang

.travis-deps.sh

@@ -4,20 +4,23 @@ set -e
 
 #if OS is linux or is not set
 if [ "$TRAVIS_OS_NAME" = linux -o -z "$TRAVIS_OS_NAME" ]; then
-    sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
-    sudo apt-get -qq update
-    sudo apt-get -qq install g++-4.8 xorg-dev libglu1-mesa-dev libxcursor-dev
+    if [ "$CXX" = "g++" ]; then
+        sudo apt-get -qq install g++-4.8
         sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 90
+        sudo update-alternatives --config c++
+    fi
+
+    sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y # GCC 4.8
+    sudo add-apt-repository ppa:kubuntu-ppa/backports -y   # CMake 2.8.12
+    sudo apt-get -qq update
+    sudo apt-get -qq install xorg-dev libglu1-mesa-dev libxcursor-dev cmake
+
     (
         git clone https://github.com/glfw/glfw.git --branch 3.0.4 --depth 1
         mkdir glfw/build && cd glfw/build
         cmake .. && make -j2 && sudo make install
     )
 
-    sudo apt-get install lib32stdc++6
-    sudo mkdir -p /usr/local
-    curl http://www.cmake.org/files/v2.8/cmake-2.8.11-Linux-i386.tar.gz \
-        | sudo tar -xz -C /usr/local --strip-components=1
 elif [ "$TRAVIS_OS_NAME" = osx ]; then
     brew tap homebrew/versions
     brew install qt5 glfw3 pkgconfig

.travis.yml

@@ -2,6 +2,10 @@ os:
   - linux
   - osx
 
+compiler:
+  - gcc
+  - clang
+
 language: cpp
 
 before_install: