Workaround unsupported (or bug?) issue in RakeCompiler:

- When the `no_native` flag is set, Rake Compiler doesn't create
  a `native` task. But when calling the `cross` task, Rake Compiler
  tries to access the `native` task to modify its prequisites.
  https://github.com/rake-compiler/rake-compiler/blob/2ac0a366be918f1e78e3f642e8d6b5bdb28fefd3/lib/rake/extensiontask.rb#L487

  This seems like a bug to me so I'll propose a fix upstream.
  But for now I'm creating a dummy `native` task.

Author: Edouard-chin

lib/cibuildgem/tasks/wrapper.rake

@@ -6,6 +6,9 @@ task = Cibuildgem::CompilationTasks.new(!Rake::Task.task_defined?(:gem))
 
 task "cibuildgem:setup" do
   task.setup
+
+  task(:native) do
+  end
 end
 
 task "copy:stage:lib" do