Disable unit tests on linux-musl

On Alpine x64, ildasm executable cannot be found. The Ilasm SDK seems to be missing linux-musl recognition in its targets: https://github.com/dotnet/runtime/blob/54625f377552300ce03100b4d1689af30395f9fd/src/coreclr/src/.nuget/Microsoft.NET.Sdk.IL/targets/Microsoft.NET.Sdk.IL.targets#L32

Author: nattress

eng/Subsets.props

@@ -150,7 +150,7 @@
                              $(CoreClrProjectRoot)src\tools\dotnet-pgo\dotnet-pgo.csproj;
                              $(CoreClrProjectRoot)src\tools\r2rtest\R2RTest.csproj" Category="clr" BuildInParallel="true" />
     <ProjectToBuild Include="$(CoreClrProjectRoot)src\tools\aot\crossgen2\crossgen2.csproj" Category="clr" />
-    <ProjectToBuild Include="$(CoreClrProjectRoot)src\tools\aot\ILCompiler.TypeSystem.ReadyToRun.Tests\ILCompiler.TypeSystem.ReadyToRun.Tests.csproj" Test="true" Category="clr" />
+    <ProjectToBuild Include="$(CoreClrProjectRoot)src\tools\aot\ILCompiler.TypeSystem.ReadyToRun.Tests\ILCompiler.TypeSystem.ReadyToRun.Tests.csproj" Test="true" Category="clr" Condition="'$(__DistroRid)' != 'linux-musl-x64'"/>
   </ItemGroup>
 
   <ItemGroup Condition="$(_subset.Contains('+clr.packages+'))">

src/coreclr/src/tools/aot/ILCompiler.TypeSystem.ReadyToRun.Tests/TestTypeSystemContext.cs

@@ -25,9 +25,7 @@ class TestTypeSystemContext : MetadataTypeSystemContext
 
         MetadataFieldLayoutAlgorithm _metadataFieldLayout = new TestMetadataFieldLayoutAlgorithm();
         MetadataRuntimeInterfacesAlgorithm _metadataRuntimeInterfacesAlgorithm = new MetadataRuntimeInterfacesAlgorithm();
-#if !READYTORUN
         ArrayOfTRuntimeInterfacesAlgorithm _arrayOfTRuntimeInterfacesAlgorithm;
-#endif
         VirtualMethodAlgorithm _virtualMethodAlgorithm = new MetadataVirtualMethodAlgorithm();
 
         public CanonicalizationMode CanonMode { get; set; } = CanonicalizationMode.RuntimeDetermined;
@@ -62,15 +60,12 @@ public override ModuleDesc ResolveAssembly(System.Reflection.AssemblyName name,
 
         public override FieldLayoutAlgorithm GetLayoutAlgorithmForType(DefType type)
         {
-#if !READYTORUN
             if (type == UniversalCanonType)
                 return UniversalCanonLayoutAlgorithm.Instance;
-#endif
 
             return _metadataFieldLayout;
         }
 
-#if !READYTORUN
         protected override RuntimeInterfacesAlgorithm GetRuntimeInterfacesAlgorithmForNonPointerArrayType(ArrayType type)
         {
             if (_arrayOfTRuntimeInterfacesAlgorithm == null)
@@ -79,7 +74,6 @@ protected override RuntimeInterfacesAlgorithm GetRuntimeInterfacesAlgorithmForNo
             }
             return _arrayOfTRuntimeInterfacesAlgorithm;
         }
-#endif
 
         protected override RuntimeInterfacesAlgorithm GetRuntimeInterfacesAlgorithmForDefType(DefType type)
         {