travis-ci: use correct package name.

.travis.yml

@@ -2,7 +2,7 @@ language: cpp
 
 before_install:
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then sudo apt-get update -qq && sudo apt-get install cmake && sudo apt-get install cmake python3 && sudo apt-get install -qq freeglut3-dev libxmu-dev libxi-dev ; fi
-  - if [ "$TRAVIS_OS_NAME" =   "osx" ]; then brew install cmake python3 freeglut3-dev libxmu-dev libxi-dev; fi
+  - if [ "$TRAVIS_OS_NAME" =   "osx" ]; then brew install cmake python3 homebrew/x11/freeglut; fi
   - echo -e "#ifndef A_R_H_INC\n#define A_R_H_INC\n#define GitVersion ${TRAVIS_JOB_ID}\n#define GitBranch \"${TRAVIS_BRANCH}\"\n#endif // A_R_H_INC" > revision.h
   # install latest LCOV (1.9 was failing)
   - cd ${TRAVIS_BUILD_DIR}