fix typo

ci/env-osx.sh

@@ -34,7 +34,8 @@
 #
 
 # TODO() - we can check if this is being sourced using $BASH_VERSION and $BASH_SOURCE[0] != ${0}.
+#
 
-if [ "${TRAVIS_OS_NAME}" = "linux" ]; then
+if [ "${TRAVIS_OS_NAME}" = "osx" ]; then
     if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.9" CC="clang-3.9"; fi
 fi