Fix building with glibc-2.16

https://bugs.gentoo.org/show_bug.cgi?id=425248

Patch written by Kacper Kowalik <xarthisius@gentoo.org>
--- a/daemon/workit.cpp
+++ b/daemon/workit.cpp
@@ -26,6 +26,7 @@
 #include "exitcode.h"
 #include "logging.h"
 #include <sys/select.h>
+#include <sys/resource.h>
 #include <algorithm>
 
 #ifdef __FreeBSD__