Fix non-portable CI builds. (dotnet#114949)

Author: tmds

eng/pipelines/runtime.yml

@@ -1786,11 +1786,12 @@ extends:
           parameters:
             platforms:
               - name: CentOS9
+                baseOS: linux-x64
                 targetRID: centos.9-x64
                 portableBuild: false
                 container: SourceBuild_centos_x64
               - name: NonexistentRID
-                baseOS: linux
+                baseOS: linux-x64
                 targetRID: banana.24-x64
                 portableBuild: false
                 container: SourceBuild_centos_x64

src/libraries/System.Runtime.InteropServices/tests/TestAssets/NativeExports/NativeExports.csproj

@@ -11,6 +11,11 @@
     <RuntimeIdentifier>$(OutputRID)</RuntimeIdentifier>
     <!-- Set the apphost RID so we download the apphost pack if needed. -->
     <AppHostRuntimeIdentifier>$(OutputRID)</AppHostRuntimeIdentifier>
+    <!--
+      If the output RID isn't the current SDK RID and we have a "base" RID, then the output RID isn't known to the SDK.
+      In that case, we need to set the AppHostRuntimeIdentifier to the base RID so the SDK can find a runtime pack for publishing.
+    -->
+    <AppHostRuntimeIdentifier Condition="'$(OutputRID)' != '$(NETCoreSdkRuntimeIdentifier)' and '$(BaseOS)' != '' ">$(BaseOS)</AppHostRuntimeIdentifier>
     <UseLocalAppHostPack>true</UseLocalAppHostPack>
     <!-- Don't use the local apphost pack on Windows as matching linker configurations is difficult. -->
     <UseLocalAppHostPack Condition="'$(TargetOS)' == 'windows'">false</UseLocalAppHostPack>