ci: build with ENABLE_WERROR on Windows

Build with -Werror's equivalent (/WX) on MSVC

Author: ethomson

ci/build.ps1

@@ -18,7 +18,7 @@ Write-Host "####################################################################
 Write-Host "## Configuring build environment"
 Write-Host "##############################################################################"
 
-Invoke-Expression "cmake ${SourceDirectory} -DBUILD_EXAMPLES=ON ${Env:CMAKE_OPTIONS}"
+Invoke-Expression "cmake ${SourceDirectory} -DBUILD_EXAMPLES=ON -DENABLE_WERROR=ON ${Env:CMAKE_OPTIONS}"
 if ($LastExitCode -ne 0) { [Environment]::Exit($LastExitCode) }
 
 Write-Host ""