Update .travis.yml

.travis.yml

@@ -119,6 +119,22 @@ matrix:
       os: linux
       addons: *clang37
 
+
+# Test gcc-4.8: C++11, Build=Debug/Release, ASAN=Off
+    - env: GCC_VERSION=4.8 BUILD_TYPE=Debug CPP=11 ASAN=Off LIBCXX=Off
+      os: linux
+      addons: &gcc48
+        apt:
+          packages:
+            - g++-4.8
+            - valgrind
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - env: GCC_VERSION=4.8 BUILD_TYPE=Release CPP=11 ASAN=Off LIBCXX=Off
+      os: linux
+      addons: *gcc48
+      
     # Test gcc-4.9: C++11, Build=Debug/Release, ASAN=Off
     - env: GCC_VERSION=4.9 BUILD_TYPE=Debug CPP=11 ASAN=Off LIBCXX=Off
       os: linux