Install GCC 4.8 on Travis.

.travis.yml

@@ -1,5 +1,13 @@
 language: cpp
 
+addons:
+  apt:
+    sources:
+    - ubuntu-toolchain-r-test
+    packages:
+    - gcc-4.8
+    - g++-4.8
+
 install:
   - sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
   - echo "deb http://download.mono-project.com/repo/debian wheezy main" | sudo tee /etc/apt/sources.list.d/mono-xamarin.list
@@ -8,6 +16,8 @@ install:
   - sudo apt-get install -y mono-devel nuget
   - build/premake5-linux-64 --file=build/premake4.lua gmake
   - nuget install NUnit.Runners -Version 2.6.4 -OutputDirectory testrunner
+  - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
+
 
 script:
   - config=debug_x32 make -C build/gmake/