Update travis-ci g++ for pzstds job
diff --git a/.travis.yml b/.travis.yml
index dc9d2fd..c84edcd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,15 @@
       env: PLATFORM="Ubuntu 12.04 container" CMD="make test && make clean && make travis-install"
     - os: linux
       sudo: false
+      install:
+        - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8" CC="gcc-4.8"; fi
+      addons:
+        apt:
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - gcc-4.8
+            - g++-4.8
       env: PLATFORM="Ubuntu 12.04 container" CMD="make -C tests test-zstd_nolegacy && make clean && make zlibwrapper && make clean && make cmaketest && make -C contrib/pzstd googletest && make -C contrib/pzstd test && make -C contrib/pzstd clean"
     - os: linux
       sudo: false