Don't use malloc.h header on OpenBSD.

--- src/lofi.cpp.orig	Mon Nov  3 22:53:48 2014
+++ src/lofi.cpp	Mon Nov  3 22:53:53 2014
@@ -24,7 +24,6 @@
 
 /*****************************************************************************/
 
-#include <malloc.h>
 #include <math.h>
 #include <stdlib.h>
 #include "cmt.h"