Build Conan package on OSX (google#4590)

- Added jobs to build Flatbuffers on OSX running on Travis

Signed-off-by: Uilian Ries <uilianries@gmail.com>

.travis.yml

@@ -4,18 +4,28 @@ env:
     - GCC_VERSION="4.9"
 
 conan-linux: &conan-linux
-   os: linux
-   sudo: required
-   language: python
-   python: "3.6"
-   services:
+  os: linux
+  sudo: required
+  language: python
+  python: "3.6"
+  services:
     - docker
-   install:
-     - pip install conan conan-package-tools
-   script:
-     - python conan/build.py
-   on:
-     tags: true
+  install:
+    - pip install conan conan-package-tools
+  script:
+    - python conan/build.py
+  on:
+    tags: true
+
+conan-osx: &conan-osx
+  os: osx
+  language: generic
+  install:
+    - ./conan/travis/osx_install.sh
+  script:
+    - ./conan/travis/osx_build.sh
+  on:
+    tags: true
 
 matrix:
   include:

conan/travis/osx_build.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -e
+set -x
+
+if [[ "$(uname -s)" == 'Darwin' ]]; then
+    if which pyenv > /dev/null; then
+        eval "$(pyenv init -)"
+    fi
+    pyenv activate conan
+fi
+
+python conan/build.py

conan/travis/osx_install.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+set -x
+
+if [[ "$(uname -s)" == 'Darwin' ]]; then
+    brew update || brew update
+    brew outdated pyenv || brew upgrade pyenv
+    brew install pyenv-virtualenv
+    brew install cmake || true
+
+    if which pyenv > /dev/null; then
+        eval "$(pyenv init -)"
+    fi
+
+    pyenv install 2.7.10
+    pyenv virtualenv 2.7.10 conan
+    pyenv rehash
+    pyenv activate conan
+fi
+
+pip install conan_package_tools # It install conan too
+conan user