ART: Add missing namespace comments

Add closing namespace comments.

Bug: 32619234
Test: m
Change-Id: I1f50e09dcd1038c4b540b87e5c19e319c1f592e4
diff --git a/compiler/debug/elf_debug_writer.h b/compiler/debug/elf_debug_writer.h
index 07f7229..5d68810 100644
--- a/compiler/debug/elf_debug_writer.h
+++ b/compiler/debug/elf_debug_writer.h
@@ -29,7 +29,7 @@
 class OatHeader;
 namespace mirror {
 class Class;
-}
+}  // namespace mirror
 namespace debug {
 struct MethodDebugInfo;