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

lib/include/ihk/debug.h

@@ -33,15 +33,6 @@
 
 #endif /* POSTK_DEBUG_ARCH_DEP_9 */
 
-struct ihk_kmsg_buf {
-	int tail;
-	int len;
-	int head;
-	int mode;
-	ihk_spinlock_t lock;
-	char str[IHK_KMSG_SIZE - sizeof(int) * 4 - sizeof(ihk_spinlock_t)];
-};
-
 extern int kprintf(const char *format, ...);
 extern unsigned long kprintf_lock(void);
 extern void kprintf_unlock(unsigned long irqflags);