init: replace Result<Success> with Result<void>

Now that Result<T> is actually expected<T, ...>, and the expected
proposal states expected<void, ...> as the way to indicate an expected
object that returns either successfully with no object or an error,
let's move init's Result<Success> to the preferred Result<void>.

Bug: 132145659
Test: boot, init unit tests
Change-Id: Ib2f98396d8e6e274f95a496fcdfd8341f77585ee
diff --git a/init/bootchart.h b/init/bootchart.h
index 05474ca..6f19aad 100644
--- a/init/bootchart.h
+++ b/init/bootchart.h
@@ -26,7 +26,7 @@
 namespace android {
 namespace init {
 
-Result<Success> do_bootchart(const BuiltinArguments& args);
+Result<void> do_bootchart(const BuiltinArguments& args);
 
 }  // namespace init
 }  // namespace android