Add a property required by #8478 (#8749)

* Add a property required by #8478

Context: #8478
Context: xamarin/monodroid#1393

Merging this no-op change will make it easier to orchestrate merging
of the two PRs above.  It allows us to merge the `monodroid` one
before merging #8478 and prevents breaking of any other builds or
PRs in between merging of the two PRs.

* Don't require it yet

* Dummy change to kick-off the build

* Undo the former change

src/Xamarin.Android.Build.Tasks/Tasks/BuildApk.cs

@@ -33,6 +33,8 @@ public class BuildApk : AndroidTask
 		[Required]
 		public string ApkOutputPath { get; set; }
 
+		public string AppSharedLibrariesDir { get; set; }
+
 		[Required]
 		public ITaskItem[] ResolvedUserAssemblies { get; set; }