Add a build for graphviz (#362)

Add a pipeline to build graphviz.  This is intended to be used for swift-doc.

Author: compnerd

.ci/graphviz.yml

@@ -0,0 +1,45 @@
+
+trigger:
+ branches:
+   include:
+     - master
+ paths:
+   include:
+     - .ci/graphviz.yml
+     - .ci/templates/graphviz.yml
+
+pool:
+  vmImage: windows-latest
+
+variables:
+  install.directory: $(Build.StagingDirectory)/graphviz-windows-x64/Library/graphviz-development
+
+steps:
+  - checkout: self
+  - script: |
+      git clone --no-tags --depth=1 https://gitlab.com/graphviz/graphviz.git
+      git -C graphviz submodule update --init
+  - task: BatchScript@1
+    inputs:
+      filename: C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/Tools/VsDevCmd.bat
+      arguments: -no_logo -arch=x64 -host_arch=x64
+      modifyEnvironment: true
+    displayName: 'VsDevCmd'
+  - task: UsePythonVersion@0
+    inputs:
+      versionSpec: 3.x
+    name: python
+  - task: CMake@1
+    inputs:
+      cmakeArgs:
+        -B $(Build.BinariesDirectory)/graphviz
+        -D BISON_EXECUTABLE=$(Build.SourcesDirectory)/graphviz/windows/dependencies/graphviz-build-utilities/winflexbison/win_bison.exe
+        -D FLEX_EXECUTABLE=$(Build.SourcesDirectory)/graphviz/windows/dependencies/graphviz-build-utilities/winflexbison/win_flex.exe
+        -D CMAKE_BUILD_TYPE=MinSizeRel
+        -D CMAKE_INSTALL_PREFIX=$(install.directory)/usr
+        -S $(Build.SourcesDirectory)/graphviz
+  - task: CMake@1
+    inputs:
+      cmakeArgs: --build $(Build.BinariesDirectory)/graphviz --target install
+  - publish: $(Build.StagingDirectory)/graphviz-windows-x64
+    artifact: graphviz-windows-x64