[build-windows-toolchain.bat] Set HOST_ARCH_NAME for script reinvocation

Follow-up to swiftlang#84326.

Author: AnthonyLatsis

utils/build-windows-toolchain.bat

@@ -23,6 +23,7 @@ echo set SKIP_PACKAGING=%SKIP_PACKAGING%>> %TEMP%\call-build.cmd
 echo set SKIP_UPDATE_CHECKOUT=%SKIP_UPDATE_CHECKOUT%>> %TEMP%\call-build.cmd
 echo set REPO_SCHEME=%REPO_SCHEME%>> %TEMP%\call-build.cmd
 echo set WINDOWS_SDKS=%WINDOWS_SDKS%>> %TEMP%\call-build.cmd
+echo set HOST_ARCH_NAME=%HOST_ARCH_NAME%>> %TEMP%\call-build.cmd
 echo "%~f0">> %TEMP%\call-build.cmd
 start /i /b /wait cmd.exe /env=default /c "%TEMP%\call-build.cmd"
 set ec=%errorlevel%