Fix passing of TargetsWindows to test group builds

Author: trylek

src/tests/build.proj

@@ -84,11 +84,13 @@
       <GroupBuildCmd>$(GroupBuildCmd) "/p:Configuration=$(Configuration)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) "/p:LibrariesConfiguration=$(LibrariesConfiguration)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) "/p:TargetOS=$(TargetOS)"</GroupBuildCmd>
+      <GroupBuildCmd>$(GroupBuildCmd) "/p:TargetsWindows=$(TargetsWindows)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) "/p:RuntimeFlavor=$(RuntimeFlavor)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) "/p:RuntimeVariant=$(RuntimeVariant)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) "/p:__TestGroupToBuild=$(__TestGroupToBuild)"</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) /p:__SkipRestorePackages=1</GroupBuildCmd>
       <GroupBuildCmd>$(GroupBuildCmd) /nodeReuse:false</GroupBuildCmd>
+      <GroupBuildCmd>$(GroupBuildCmd) /maxcpucount</GroupBuildCmd>
     </PropertyGroup>
 
     <Message Importance="High" Text="$(MsgPrefix)Building managed test group $(__TestGroupToBuild): $(GroupBuildCmd)" />