[parisc-linux] ldcw in __pthread_acquire

[LaMont Jones]

> Thats how Mozilla does it, and with a short spin in user space performance
> is way higher than always bugging the kernel

The hp-ux implementation of msem_lock() takes the advantages of both:
Gateway to kernel mode (very light weight - one predicted branch beyond
the function call), and then it does the spin and wait as needed.  Very
low cost, with the kernel-mode blocking easier to do that a combined
user-and-kernel-mode implementation.

Just my $.02,
lamont