Implement << operator for DexRegisterLocation::Kind.

This makes it comparable in DCHECK_EQ and similar methods.

Change-Id: I6b5b237be89325850ae6860d011fd6741189ab01
diff --git a/compiler/debug/elf_debug_loc_writer.h b/compiler/debug/elf_debug_loc_writer.h
index 8fd20aa..32f624a 100644
--- a/compiler/debug/elf_debug_loc_writer.h
+++ b/compiler/debug/elf_debug_loc_writer.h
@@ -232,8 +232,7 @@
         // kInStackLargeOffset and kConstantLargeValue are hidden by GetKind().
         // kInRegisterHigh and kInFpuRegisterHigh should be handled by
         // the special cases above and they should not occur alone.
-        LOG(ERROR) << "Unexpected register location kind: "
-                   << DexRegisterLocation::PrettyDescriptor(kind);
+        LOG(ERROR) << "Unexpected register location kind: " << kind;
         break;
       }
       if (is64bitValue) {