The devstat(3) manpage claims that only <devstat.h> is needed as a

prerequisite for using this interface.  However, the 'statinfo' struct
actually references CPUSTATES from <sys/resource.h>, so in fact it
requires <sys/resource.h> to compile.  Use a nested include of
<sys/resource.h> to make the code match the docs.

Reported by:	Pietro Cerutti  gahr | gahr.ch

lib/libdevstat/devstat.h

@@ -32,6 +32,7 @@
 #define _DEVSTAT_H
 #include <sys/cdefs.h>
 #include <sys/devicestat.h>
+#include <sys/resource.h>
 
 #include <kvm.h>