build: add more checking for errors

Apply more error checking to ensure that failures do not slip through
the various layers of invocation.

Author: compnerd

utils/build-windows-toolchain.bat

@@ -25,8 +25,9 @@ echo set SKIP_UPDATE_CHECKOUT=%SKIP_UPDATE_CHECKOUT%>> %TEMP%\call-build.cmd
 echo set REPO_SCHEME=%REPO_SCHEME%>> %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%
 del %TEMP%\call-build.cmd
-exit /b
+exit /b %ec%
 
 :Start
 
@@ -80,7 +81,7 @@ powershell.exe -ExecutionPolicy RemoteSigned -File %~dp0build.ps1 ^
   -BuildType %CMAKE_BUILD_TYPE% ^
   %SkipPackagingArg% ^
   %TestArg% ^
-  -Stage %PackageRoot%
+  -Stage %PackageRoot% || (exit /b)
 
 :: Clean up the module cache
 rd /s /q %LocalAppData%\clang\ModuleCache