Move headers under the hf directory.

This helps distinguish local headers from the more official headers.

Change-Id: I535c1b44081b9d60ba63666cd1ad514aaaf2c68d
diff --git a/test/vm/hf_test.h b/test/vm/hf_test.h
index 2959ff5..4a1acc3 100644
--- a/test/vm/hf_test.h
+++ b/test/vm/hf_test.h
@@ -4,7 +4,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "dlog.h"
+#include "hf/dlog.h"
 
 /*
  * Prefixed to log lines from tests for easy filtering in the console.