win,build,tools: support VS prerelease

PR-URL: #36033
Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

tools/msvs/vswhere_usability_wrapper.cmd

@@ -5,7 +5,7 @@
 
 @if not defined DEBUG_HELPER @ECHO OFF
 setlocal
-if "%~1"=="prerelease" set VSWHERE_WITH_PRERELEASE=1
+if "%~2"=="prerelease" set VSWHERE_WITH_PRERELEASE=1
 set "InstallerPath=%ProgramFiles(x86)%\Microsoft Visual Studio\Installer"
 if not exist "%InstallerPath%" set "InstallerPath=%ProgramFiles%\Microsoft Visual Studio\Installer"
 if not exist "%InstallerPath%" goto :no-vswhere

vcbuild.bat

@@ -249,7 +249,7 @@ echo Looking for Visual Studio 2019
 @rem cleared first as vswhere_usability_wrapper.cmd doesn't when it fails to
 @rem detect the version searched for
 if not defined target_env set "VCINSTALLDIR="
-call tools\msvs\vswhere_usability_wrapper.cmd "[16.0,17.0)"
+call tools\msvs\vswhere_usability_wrapper.cmd "[16.0,17.0)" "prerelease"
 if "_%VCINSTALLDIR%_" == "__" goto vs-set-2017
 set "WIXSDKDIR=%WIX%\SDK\VS2017"
 if defined msi (