ENH: Use recommended homebrew addon for travis.

Remove unnecessary python3 environment from osx that
made configuring the test environment slower.

Use "addon:" features for installing homebrew
packages more efficiently.

Re-organized the .travis.yml file in a standard
order so that the "before-install" and "install"
steps occur after the configurations of addons and
 matrix, and language features are set.

.travis.yml

@@ -5,12 +5,12 @@
 # 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
-
-before_install:
-- source travis.before_install.${TRAVIS_OS_NAME}.sh
-install:
-- source travis.install.${TRAVIS_OS_NAME}.sh
+language: cpp
+sudo: false
 addons:
+  homebrew:
+    packages: meson ninja
+    update: false # do not update homebrew by default
   apt:
     sources:
     #- ubuntu-toolchain-r-test
@@ -20,16 +20,16 @@ addons:
     #- g++-4.9
     - clang-3.5
     - valgrind
-language: cpp
-script: ./travis.sh
 matrix:
   allow_failures:
     - os: osx
-matrix:
   include:
     - os: osx
       osx_image: xcode9.4
       compiler: clang
+      addons:
+         homebrew:
+         packages: meson ninja
       #env: PYENV_ROOT=/usr/local/var/pyenv
       env: LIB_TYPE=static BUILD_TYPE=release HOMEBREW_LOGS=~/homebrew-logs HOMEBREW_TEMP=~/homebrew-temp
       #- LIB_TYPE=shared BUILD_TYPE=debug
@@ -39,4 +39,9 @@ matrix:
       env: LIB_TYPE=static BUILD_TYPE=release
 notifications:
   email: false
-sudo: false
+
+before_install:
+- source ./travis.before_install.${TRAVIS_OS_NAME}.sh
+install:
+- source ./travis.install.${TRAVIS_OS_NAME}.sh
+script: ./travis.sh

travis.before_install.osx.sh

@@ -1,3 +1,5 @@
-set -vex
+# NOTHING TO DO HERE
+# set -vex
+ 
 #brew install pyenv
 #which pyenv

travis.install.osx.sh

@@ -1,12 +1,5 @@
-set -vex
+# NOTHING TO DO HERE
+# set -vex
 
-#brew update
-brew upgrade python3
-python3 -m venv venv
-source venv/bin/activate
-
-brew install ninja
-brew install meson
-
-#brew install pyenv
-#which pyenv
+#python3 -m venv venv
+#source venv/bin/activate

travis.sh

@@ -17,6 +17,9 @@ set -vex
 
 env | sort
 
+which python3
+which meson
+which ninja
 echo ${CXX}
 ${CXX} --version
 python3 --version