[$] NUMA-aware qspinlocks

While some parts of the core kernel reached a relatively stable "done"state years ago, others never really seem to be finished. One of thelatter variety is undoubtedly the kernel's implementation of spinlocks,which arbitrate access to data at the lowest levels of the kernel. Lockperformance can have a significant effect on the performance of the systemas a whole, so optimization work can pay back big dividends. Lest onethink that this work is finally done, the NUMA-awareqspinlock patch set shows how some more performance can be squeezed outof the kernel's spinlock implementation.