Merge pull request #2100 from ngie-eign/test-clang-osx-every-travis-run

Test out changes with clang/OSX each PR using Travis CI

.travis.yml

@@ -48,8 +48,8 @@ matrix:
       compiler: gcc
       env: BUILD_TYPE=Release VERBOSE=1 CXX_FLAGS=-std=c++11 HOMEBREW_LOGS=~/homebrew-logs HOMEBREW_TEMP=~/homebrew-temp
     - os: osx
+      compiler: clang
       env: BUILD_TYPE=Release VERBOSE=1 CXX_FLAGS=-std=c++11 HOMEBREW_LOGS=~/homebrew-logs HOMEBREW_TEMP=~/homebrew-temp
-      if: type != pull_request
 
 # These are the install and build (script) phases for the most common entries in the matrix.  They could be included
 # in each entry in the matrix, but that is just repetitive.
@@ -73,6 +73,13 @@ addons:
     packages:
     - g++-4.9
     - clang-3.9
+    update: true
+  homebrew:
+    packages:
+    - ccache
+    - gcc@4.9
+    - llvm@3.9
+    update: true
 
 notifications:
   email: false