Merge from amd64-branch:

Merge from amd64-branch:
44886 KxAcquireSpinLock: check for already owned lock only on debug builds, fix check in inner loop, don't call Kii386SpinOnSpinLock inside the inner loop, but instead of it, simplify the code. Stubplement Kii386SpinOnSpinLock in C
44893 Move spinlock inline functions into their own header, so they can be shared with hal.

svn path=/trunk/; revision=45196