Update clang version

.travis.yml

@@ -2,15 +2,12 @@
 # http://about.travis-ci.org/docs/user/build-configuration/
 # This file can be validated on:
 # http://lint.travis-ci.org/
-# See also
-# http://stackoverflow.com/questions/22111549/travis-ci-with-clang-3-4-and-c11/30925448#30925448
-# to allow C++11, though we are not yet building with -std=c++11
 
 install:
 # /usr/bin/gcc is 4.6 always, but gcc-X.Y is available.
 - if [ "$CXX" = "g++" ]; then export CXX="g++-4.9" CC="gcc-4.9"; fi
-# /usr/bin/clang is our version already, and clang-X.Y does not exist.
-#- if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.7" CC="clang-3.7"; fi
+# /usr/bin/clang is 3.4, lets override with modern one.
+- if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.7" CC="clang-3.7"; fi
 - echo ${PATH}
 - echo ${CXX}
 - ${CXX} --version
@@ -19,11 +16,11 @@ addons:
   apt:
     sources:
     - ubuntu-toolchain-r-test
-    - llvm-toolchain-precise-3.6
+    - llvm-toolchain-precise-3.7
     packages:
     - gcc-4.9
     - g++-4.9
-    - clang-3.6
+    - clang-3.7
     - valgrind
 os:
   - linux