rusage and ihklib: Fix out-of-memory reporting and cleanup

1. Fix OOM: Count memory usage only when allocation succeeded
2. Fix OOM: Make user allocation fail when memory is running out
3. Fix OOM: Move rusage_init() before numa_init()
4. Cleanup: Rename ihkconfig/ihkosctl functions
5. Cleanup: Pass event type to eventfd()
6. Cleanup: arch/.../rusage.h --> arch/.../arch_rusage.h

kernel/include/syscall.h

@@ -268,6 +268,11 @@ struct ikc_scd_packet {
 			enum mcctrl_os_cpu_operation op;
 			void *resp;
 		};
+
+		/* SCD_MSG_EVENTFD */
+		struct {
+			int eventfd_type;
+		};
 	};
 	char padding[12];
 };