Re-enable signing of System.Private.CoreLib (#22068)

* Re-enable signing for System.Private.CoreLib

Now that dotnet/arcade#1582 is fixed.
Addresses https://github.com/dotnet/coreclr/issues/21946.

* Use uppercase build config

For consistency with other builds. Doesn't impact functionality, but
will result in the build logs showing the bin directory with the
uppercase build config during this step.

* Override arcade version of SignTool package

eng/Signing.props

@@ -47,11 +47,6 @@
       <Output TaskParameter="SigningMetadata" ItemName="ItemsToSign" />
     </ReadSigningRequired>
 
-    <!-- Temporarily disable signing CoreLib due to https://github.com/dotnet/arcade/issues/1582 -->
-    <ItemGroup>
-      <ItemsToSign Remove="$(BinDir)System.Private.CoreLib.dll" />
-    </ItemGroup>
-
     <Message Importance="High" Text="Attempting to sign %(ItemsToSign.Identity) with authenticode='%(ItemsToSign.Authenticode)' and strongname='%(ItemsToSign.StrongName)'" />
   </Target>
 

eng/Versions.props

@@ -10,6 +10,11 @@
     <MicrosoftNetFrameworkReferenceAssembliesVersion>1.0.0-alpha-004</MicrosoftNetFrameworkReferenceAssembliesVersion>
     <!-- Libs -->
   </PropertyGroup>
+  <PropertyGroup>
+    <!-- Override arcade package version to use most recent signing
+         package -->
+    <MicrosoftDotNetSignToolVersion>1.0.0-beta.19067.6</MicrosoftDotNetSignToolVersion>
+  </PropertyGroup>
   <PropertyGroup>
     <RestoreSources>
       $(RestoreSources);

eng/build-job.yml

@@ -92,7 +92,7 @@ jobs:
 
     # Sign on Windows
     - ${{ if and(ne(variables['System.TeamProject'], 'public'), ne(variables['Build.Reason'], 'PullRequest'), eq(parameters.osGroup, 'Windows_NT')) }}:
-      - script: powershell eng\common\build.ps1 -ci -sign -restore -configuration:$(buildConfig) -warnaserror:0 /p:ArcadeBuild=true /p:OfficialBuild=true /p:BuildOS=$(osGroup) /p:BuildArch=$(archType) /p:BuildType=$(buildConfig) /p:DotNetSignType=%_SignType% -projects $(Build.SourcesDirectory)\eng\empty.proj
+      - script: powershell eng\common\build.ps1 -ci -sign -restore -configuration:$(buildConfig) -warnaserror:0 /p:ArcadeBuild=true /p:OfficialBuild=true /p:BuildOS=$(osGroup) /p:BuildArch=$(archType) /p:BuildType=$(buildConfigUpper) /p:DotNetSignType=%_SignType% -projects $(Build.SourcesDirectory)\eng\empty.proj
         displayName: Sign Binaries
 
       - task: PublishBuildArtifacts@1