CLRBUSY
next = CLRBUSY(blk->nextblk);
next = CLRBUSY(blk->nextblk);
brk(CLRBUSY(arena[1].nextblk));
lblk = (struct lblk *)CLRBUSY((char *)ptr - MINHEAD);
blk->nextblk = next = CLRBUSY(next);
next = CLRBUSY(next);
blk = CLRBUSY(arena[1].nextblk);
next = CLRBUSY(blk->nextblk);