AP: Add one Xcode build.

[skip travis] [skip appveyor]

azure-pipelines.yml

@@ -18,6 +18,7 @@ jobs:
         TOOLSET: gcc
         TEST_TOOLSET: gcc
         CXX: g++-8
+        PACKAGES: g++-8
   steps:
   - task: UsePythonVersion@0
     inputs:
@@ -28,8 +29,7 @@ jobs:
         set -e
         uname -a
         sudo -E apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
-        sudo -E apt-get -yq --no-install-suggests --no-install-recommends install g++-8
-        which g++-8
+        sudo -E apt-get -yq --no-install-suggests --no-install-recommends install ${PACKAGES}
     displayName: Install
   - bash: |
         set -e
@@ -82,3 +82,40 @@ jobs:
         python test_all.py $env:TEST_TOOLSET
         cd ..
     displayName: Test
+
+- job: 'macOS'
+  pool:
+    vmImage: 'macOS-10.13'
+  strategy:
+    matrix:
+      Xcode 10.1:
+        TOOLSET: clang
+        TEST_TOOLSET: clang
+        CXX: clang++
+        XCODE_APP: /Applications/Xcode_10.1.app
+  steps:
+  - task: UsePythonVersion@0
+    inputs:
+      versionSpec: '2.7'
+      architecture: 'x64'
+      addToPath: true
+  - bash: |
+        set -e
+        uname -a
+        sudo xcode-select -switch ${XCODE_APP}
+        which clang++
+    displayName: Install
+  - bash: |
+        set -e
+        cd src/engine
+        ./build.sh ${TOOLSET}
+        cd ../..
+    displayName: Build
+  - bash: |
+        set -e
+        CXX_PATH=`which ${CXX}`
+        cd test
+        echo "using ${TEST_TOOLSET} : : ${CXX_PATH} ;" > ${HOME}/user-config.jam
+        python test_all.py ${TEST_TOOLSET}
+        cd ..
+    displayName: Test