ihk_os_getrusage(): Compile LWK-specific results in mcctrl

1. User asks mcctrl for the result via ihk_os_getrusage() with passing void *
2. mcctrl compiles the results and passes them to the user
3. User interprets it by using the type defined in the LWK-specific header

lib/include/ihk/monitor.h

@@ -0,0 +1,8 @@
+#ifndef MONITOR_H_INCLUDED
+#define MONITOR_H_INCLUDED
+
+#include <ihk/ihk_monitor.h>
+
+extern struct ihk_os_monitor *monitor;
+
+#endif /* !defined(MONITOR_H_INCLUDED) */