AAPT2: Fix debugging output

Test: manual
Change-Id: I3a362caf7bd691df399db00c6280e0a208a406da
diff --git a/tools/aapt2/Debug.cpp b/tools/aapt2/Debug.cpp
index 08efc27..0f6fb50 100644
--- a/tools/aapt2/Debug.cpp
+++ b/tools/aapt2/Debug.cpp
@@ -218,6 +218,7 @@
       if (attr.id) {
         printer_->Print(attr.id.value().to_string());
       }
+      printer_->Println();
     }
   }