Update Travis-CI config for C++ integration.

.travis.yml

@@ -1,27 +1,24 @@
-language: c
+language: generic
 
 matrix:
   include:
     - os: linux
-      compiler: gcc
+      env: CC=gcc CXX=g++
+      env: CC=clang CXX=clang++
     - os: linux
-      compiler: gcc
-      env:
-        - EXTRA_FLAGS=-m32
+      env: CC=gcc CXX=g++ EXTRA_FLAGS=-m32
+      env: CC=clang CXX=clang++ EXTRA_FLAGS=-m32
       addons:
         apt:
           packages:
           - gcc-multilib
     - os: osx
-      compiler: clang
-    - os: osx
-      compiler: clang
-      env:
-        - EXTRA_FLAGS=-m32
+      env: CC=clang CXX=clang++
+      env: CC=clang CXX=clang++ EXTRA_FLAGS=-m32
 
 before_script:
   - autoconf
-  - ./configure${EXTRA_FLAGS:+ CC="$CC $EXTRA_FLAGS"}
+  - ./configure${EXTRA_FLAGS:+ CC="$CC $EXTRA_FLAGS" CXX="$CXX $EXTRA_FLAGS"}
   - make -j3
   - make -j3 tests