Support building with VS2019 Preview (#22525)

* Support building with VS2019 Preview

* Fixing gen-buildsys-win to only set the architecture for the VS generator

* Refactoring Dev11/147911/fpcw.cpp so that it compiles under VS2019

* Removing the remaining traces of VS2015 build support

1 files changed, 3 insertions, 9 deletions

diff --git a/Documentation/building/windows-instructions.md b/Documentation/building/windows-instructions.md
index cfd6293e3b..b526148895 100644
--- a/Documentation/building/windows-instructions.md
+++ b/Documentation/building/windows-instructions.md
@@ -11,13 +11,8 @@ You must install several components to build the CoreCLR and CoreFX repos. These
 ## Visual Studio
 
 Visual Studio must be installed. Supported versions:
-- [Visual Studio 2015](https://www.visualstudio.com/vs/older-downloads/) (Community, Professional, Enterprise).  The community version is completely free.  
 - [Visual Studio 2017](https://www.visualstudio.com/downloads/) (Community, Professional, Enterprise).  The community version is completely free.  
-
-For Visual Studio 2015:
-* Ensure you have installed at least [Visual Studio 2015 Update 3](https://www.visualstudio.com/en-us/news/releasenotes/vs2015-update3-vs).
-* Make sure that you install "VC++ Tools". By default, they will not be installed.
-* To build for Arm32, Make sure that you have the Windows SDK for Windows 10 installed (or selected to be installed as part of VS installation). To explicitly install Windows SDK, download it from here: [Windows SDK for Windows 10](https://developer.microsoft.com/en-us/windows/downloads)
+- [Visual Studio 2019 Preview](https://visualstudio.microsoft.com/vs/preview/) (Community, Professional, Enterprise).  The community version is completely free.  
 
 For Visual Studio 2017:
 * When doing a 'Workloads' based install, the following are the minimum requirements:
@@ -50,7 +45,6 @@ For Visual Studio 2017:
 * **Important:** You must have the `msdia120.dll` COM Library registered in order to build the repository.
   * This binary is registered by default when installing the "VC++ Tools" with Visual Studio 2015
   * You can also manually register the binary by launching the "Developer Command Prompt for VS2017" with Administrative privileges and running `regsvr32.exe "%VSINSTALLDIR%\Common7\IDE\msdia120.dll"`
-* **Important:** By default, the build will attempt to use VS2015 as the toolset for the build. To build using VS2017 as your toolset, you must use the "Developer Command Prompt for VS2017".
 
 Visual Studio Express is not supported.
 
@@ -75,7 +69,7 @@ any recent (2.4+) version of Python should work, including Python 3.
 
 ## Git
 
-For actual user operations, it is often more convenient to use the GIT features built into Visual Studio 2015.
+For actual user operations, it is often more convenient to use the GIT features built into Visual Studio.
 However the CoreCLR and the tests use the GIT command line utilities directly so you need to install them
 for these to work properly.   You can get it from 
 
@@ -93,7 +87,7 @@ Powershell version must be 3.0 or higher. This should be the case for Windows 8
 
 ## DotNet Core SDK
 While not strictly needed to build or test the .NET Core repository, having the .NET Core SDK installed lets you use the dotnet.exe command to run .NET Core applications in the 'normal' way.   We use this in the 
-[Using Your Build](../workflow/UsingYourBuild.md) instructions.  Visual Studio 2015 (update 3) should have
+[Using Your Build](../workflow/UsingYourBuild.md) instructions.  Visual Studio should have
 installed the .NET Core SDK, but in case it did not you can get it from the [Installing the .Net Core SDK](https://www.microsoft.com/net/core) page.  
 
 ## Adding to the default PATH variable