C++17 compatibility: make WITH_TIDY=1 happy again.

Bug: http://b/111067277
Test: builds
Change-Id: I8b69ea3815e14bb6eb27f40c0dd01a85b340a355
diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index fe61547..e52a1c9 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -1876,7 +1876,7 @@
     default:
       LOG(FATAL) << "Unsupported primitive type " << primitive_component_type
                  << " in fill-array-data";
-      break;
+      UNREACHABLE();
   }
 }