Implement << operator for DexRegisterLocation::Kind.

This makes it comparable in DCHECK_EQ and similar methods.

Change-Id: I6b5b237be89325850ae6860d011fd6741189ab01
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 5faff93..b1f1ed6 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -352,12 +352,11 @@
       return false;
     default:
       LOG(FATAL)
-          << "Unexpected location kind"
-          << DexRegisterLocation::PrettyDescriptor(
-                dex_register_map.GetLocationInternalKind(vreg,
-                                                         number_of_dex_registers,
-                                                         code_info,
-                                                         encoding));
+          << "Unexpected location kind "
+          << dex_register_map.GetLocationInternalKind(vreg,
+                                                      number_of_dex_registers,
+                                                      code_info,
+                                                      encoding);
       UNREACHABLE();
   }
 }