Do not bundle the ILCompiler (NativeAOT) where unsupported (e.g. ppc64le)

Gate BundleNativeAotCompiler on the NativeAotSupported feature flag instead of
attempting to bundle the ILCompiler/NativeAOT packs on RIDs that have no
NativeAOT backend. eng/common/native/NativeAotSupported.props already excludes
ppc64le (and s390x, wasm, and the unsupported OSes), so the source build no
longer tries to restore the nonexistent freebsd-ppc64le ILCompiler packs.

Author: pkubaj

src/Layout/Directory.Build.props

@@ -74,10 +74,12 @@
       )">true</SkipBuildingInstallers>
   </PropertyGroup>
 
+  <Import Project="$(RepositoryEngineeringDir)common\native\NativeAotSupported.props" />
+
   <PropertyGroup>
     <GenerateSdkBundleOnly Condition="'$(DotNetBuildPass)' == '3' and '$(OS)' == 'Windows_NT'">true</GenerateSdkBundleOnly>
     <BundleRuntimePacks Condition="'$(BundleRuntimePacks)' == '' and '$(DotNetBuildSourceOnly)' == 'true'">true</BundleRuntimePacks>
-    <BundleNativeAotCompiler Condition="'$(BundleNativeAotCompiler)' == '' and '$(DotNetBuildSourceOnly)' == 'true' and '$(DotNetBuildUseMonoRuntime)' != 'true'">true</BundleNativeAotCompiler>
+    <BundleNativeAotCompiler Condition="'$(BundleNativeAotCompiler)' == '' and '$(DotNetBuildSourceOnly)' == 'true' and '$(DotNetBuildUseMonoRuntime)' != 'true' and '$(NativeAotSupported)' == 'true'">true</BundleNativeAotCompiler>
 
     <!-- Crossgen2 is not bundled by default on platforms where Microsoft provides a package on nuget.org,
          because it is large (100MB+). -->