Avoid building Windows-only binaries on linux/mac

Author: AArnott

Microsoft.VisualStudio.Threading.slnx

@@ -44,9 +44,13 @@
     <File Path="test/Directory.Build.targets" />
     <File Path="test/dirs.proj" />
     <Project Path="samples/samples.csproj" />
-    <Project Path="test/IsolatedTestHost/IsolatedTestHost.csproj" />
+    <Project Path="test/IsolatedTestHost/IsolatedTestHost.csproj">
+      <Build Solution="*|NonWindows" Project="false" />
+    </Project>
     <Project Path="test/Microsoft.VisualStudio.Threading.Analyzers.Tests/Microsoft.VisualStudio.Threading.Analyzers.Tests.csproj" />
-    <Project Path="test/Microsoft.VisualStudio.Threading.Tests.Win7RegistryWatcher/Microsoft.VisualStudio.Threading.Tests.Win7RegistryWatcher.csproj" />
+    <Project Path="test/Microsoft.VisualStudio.Threading.Tests.Win7RegistryWatcher/Microsoft.VisualStudio.Threading.Tests.Win7RegistryWatcher.csproj">
+      <Build Solution="*|NonWindows" Project="false" />
+    </Project>
     <Project Path="test/Microsoft.VisualStudio.Threading.Tests/Microsoft.VisualStudio.Threading.Tests.csproj" />
     <Project Path="test/NativeAOTCompatibility.Test/NativeAOTCompatibility.Test.csproj" />
   </Folder>

tools/dotnet-test-cloud.ps1

@@ -47,6 +47,11 @@ if ($x86) {
 $testBinLog = Join-Path $ArtifactStagingFolder (Join-Path build_logs test.binlog)
 $testDiagLog = Join-Path $ArtifactStagingFolder (Join-Path test_logs diag.log)
 
+$extraArgs = @()
+if ($IsLinux -or $IsMacOS) {
+    $extraArgs += '-p:Platform=NonWindows'
+}
+
 & $dotnet test $RepoRoot `
     --no-build `
     -c $Configuration `
@@ -58,6 +63,7 @@ $testDiagLog = Join-Path $ArtifactStagingFolder (Join-Path test_logs diag.log)
     -bl:"$testBinLog" `
     --diag "$testDiagLog;TraceLevel=info" `
     --logger trx `
+    @extraArgs `
 
 $unknownCounter = 0
 Get-ChildItem -Recurse -Path $RepoRoot\test\*.trx |% {