Merge branch 'en/oidset-uninclude-hashmap'

Code clean-up.

* en/oidset-uninclude-hashmap:
  oidset: remove unnecessary include
diff --git a/oidset.h b/oidset.h
index 5346563..d8a106b 100644
--- a/oidset.h
+++ b/oidset.h
@@ -1,7 +1,6 @@
 #ifndef OIDSET_H
 #define OIDSET_H
 
-#include "hashmap.h"
 #include "khash.h"
 
 /**