Add an osx Travis build. (#148)

Author: Ian Sturdy

.travis.yml

@@ -1,15 +1,24 @@
 language: cpp
-os: linux
-dist: trusty
-sudo: false
+matrix:
+  include:
+    - os: linux
+      dist: trusty
+      sudo: false
+      env: BAZEL_OS=linux
+    - os: osx
+      env: BAZEL_OS=darwin
+
 compiler: clang
 env: BAZEL_OPTIONS="--local_resources=4096,2,1.0 --copt=-Werror=thread-safety"
 
 before_install:
-  - tools/format.sh
-  - wget https://github.com/bazelbuild/bazel/releases/download/0.11.1/bazel-0.11.1-installer-linux-x86_64.sh
-  - chmod +x bazel-0.11.1-installer-linux-x86_64.sh
-  - ./bazel-0.11.1-installer-linux-x86_64.sh --user
+  # OS X does not have clang-format by default, and has a different sed.
+  - if \[ "$TRAVIS_OS_NAME" == "linux" \]; then
+      tools/format.sh ;
+    fi
+  - wget https://github.com/bazelbuild/bazel/releases/download/0.11.1/bazel-0.11.1-installer-${BAZEL_OS}-x86_64.sh
+  - chmod +x bazel-0.11.1-installer-${BAZEL_OS}-x86_64.sh
+  - ./bazel-0.11.1-installer-${BAZEL_OS}-x86_64.sh --user
 
 script:
   # We can't use --noshow_progress because Travis terminates the

tools/bazel.rc

@@ -1,6 +1,9 @@
 # bazel configurations for running tests under sanitizers.
 # Based on https://github.com/bazelment/trunk/blob/master/tools/bazel.rc
 
+# Needed by gRPC to build on some platforms.
+build --copt -DGRPC_BAZEL_BUILD
+
 # --config=asan : Address Sanitizer.
 common:asan --copt -fsanitize=address
 common:asan --copt -DADDRESS_SANITIZER