Python wheel kokoro for windows (#5034)

* Add kokoro config for building python wheels on windows

* Move script to root

* Debug

* Debug

* Change working directory

* Add msbuild to path

* Debug

* Fix python dir name

* Debug

* Move artifacts to targeted directory

* Update artifact directory

* Debug

* Debug

* Automatic generation of version

* Reduce file numbers

kokoro/release/python/windows/build_artifacts.bat

+REM Move scripts to root
+cd github\protobuf
+copy kokoro\release\python\windows\build_single_artifact.bat build_single_artifact.bat
+
+REM Set environment variables
+set REPO_DIR=protobuf
+set PACKAGE_NAME=protobuf
+set BUILD_DLL=OFF
+set UNICODE=ON
+set PB_TEST_DEP="six==1.9"
+set OTHER_TEST_DEP="setuptools==38.5.1"
+set OLD_PATH=C:\Program Files (x86)\MSBuild\14.0\bin\;%PATH%
+for /f "tokens=*" %%i in ( 'grep -i "version" python/google/protobuf/__init__.py ^| grep -o "'.*'"' ) do set BUILD_VERSION=%%i
+set BUILD_COMMIT=v%BUILD_VERSION:'=%
+
+REM Fetch multibuild
+git clone https://github.com/matthew-brett/multibuild.git
+
+REM Install zlib
+mkdir zlib
+curl -L -o zlib.zip http://www.winimage.com/zLibDll/zlib123dll.zip
+curl -L -o zlib-src.zip http://www.winimage.com/zLibDll/zlib123.zip
+7z x zlib.zip -ozlib
+7z x zlib-src.zip -ozlib\include
+SET ZLIB_ROOT=%cd%\zlib
+del /Q zlib.zip
+del /Q zlib-src.zip
+
+REM Create directory for artifacts
+SET ARTIFACT_DIR=%cd%\artifacts
+mkdir %ARTIFACT_DIR%
+
+REM Build wheel
+
+SET PYTHON=C:\python35_32bit
+SET PYTHON_VERSION=3.5
+SET PYTHON_ARCH=32
+CALL build_single_artifact.bat
+
+SET PYTHON=C:\python35
+SET PYTHON_VERSION=3.5
+SET PYTHON_ARCH=64
+CALL build_single_artifact.bat
+
+SET PYTHON=C:\python36_32bit
+SET PYTHON_VERSION=3.6
+SET PYTHON_ARCH=32
+CALL build_single_artifact.bat
+
+SET PYTHON=C:\python36
+SET PYTHON_VERSION=3.6
+SET PYTHON_ARCH=64
+CALL build_single_artifact.bat

kokoro/release/python/windows/build_single_artifact.bat

+setlocal
+
+if %PYTHON%==C:\python35_32bit set generator=Visual Studio 14
+if %PYTHON%==C:\python35_32bit set vcplatform=Win32
+
+if %PYTHON%==C:\python35 set generator=Visual Studio 14 Win64
+if %PYTHON%==C:\python35 set vcplatform=x64
+
+if %PYTHON%==C:\python36_32bit set generator=Visual Studio 14
+if %PYTHON%==C:\python36_32bit set vcplatform=Win32
+
+if %PYTHON%==C:\python36 set generator=Visual Studio 14 Win64
+if %PYTHON%==C:\python36 set vcplatform=x64
+
+REM Prepend newly installed Python to the PATH of this build (this cannot be
+REM done from inside the powershell script as it would require to restart
+REM the parent CMD process).
+SET PATH=%PYTHON%;%PYTHON%\Scripts;%OLD_PATH%
+python -m pip install -U pip
+pip install wheel
+
+REM Check that we have the expected version and architecture for Python
+python --version
+python -c "import struct; print(struct.calcsize('P') * 8)"
+
+rmdir /s/q protobuf
+git clone https://github.com/google/protobuf.git
+
+REM Checkout release commit
+cd %REPO_DIR%
+git checkout %BUILD_COMMIT%
+
+REM ======================
+REM Build Protobuf Library
+REM ======================
+
+mkdir src\.libs
+
+mkdir vcprojects
+pushd vcprojects
+cmake -G "%generator%" -Dprotobuf_BUILD_SHARED_LIBS=%BUILD_DLL% -Dprotobuf_UNICODE=%UNICODE% -Dprotobuf_BUILD_TESTS=OFF ../cmake
+msbuild protobuf.sln /p:Platform=%vcplatform% /p:Configuration=Release
+dir /s /b
+popd
+copy vcprojects\Release\libprotobuf.lib src\.libs\libprotobuf.a
+copy vcprojects\Release\libprotobuf-lite.lib src\.libs\libprotobuf-lite.a
+SET PATH=%cd%\vcprojects\Release;%PATH%
+dir vcprojects\Release
+
+REM ======================
+REM Build python library
+REM ======================
+
+cd python
+
+REM sed -i 's/\ extra_compile_args\ =\ \[\]/\ extra_compile_args\ =\ \[\'\/MT\'\]/g' setup.py
+
+python setup.py bdist_wheel --cpp_implementation --compile_static_extension
+dir dist
+copy dist\* %ARTIFACT_DIR%
+dir %ARTIFACT_DIR%
+cd ..\..

kokoro/release/python/windows/release.cfg

+# Configuration for Windows protoc release builds
+build_file: "protobuf/kokoro/release/python/windows/build_artifacts.bat"
+
+action {
+  define_artifacts {
+    regex: "github/protobuf/artifacts/**"
+  }
+}