Revert "g++"

This reverts commit 6812e9b7.

.travis.yml

@@ -7,25 +7,20 @@ dist: trusty
 osx_image: xcode8
 addons:
   ssh_known_hosts:
-    - github.com
+  - github.com
   apt:
-    sources:
-      - ubuntu-toolchain-r-test
     packages:
-      - gcc-6
-      - g++-6
-      - libfreetype6-dev
-      - libevent-dev
-      - libsqlite3-dev
-      - libirrlicht-dev
-      - libgl1-mesa-dev
-      - libglu-dev
-      - p7zip-full
+    - libfreetype6-dev
+    - libevent-dev
+    - libsqlite3-dev
+    - libirrlicht-dev
+    - libgl1-mesa-dev
+    - libglu-dev
+    - p7zip-full
 env:
 - USE_IRRKLANG=1
 before_install:
 - git submodule update --init --recursive
-- if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then sudo ln -s /usr/bin/gcc-6 /usr/local/bin/gcc; sudo ln -s /usr/bin/g++-6 /usr/local/bin/g++; fi
 - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
     brew update > /dev/null;
     brew install freetype libevent sqlite p7zip dylibbundler > /dev/null;