Use constant generating tricks for XMVectorSplatOne, etc.

[walbourn]

In the original Xbox 360 implementation of xboxmath, the following functions used tricks and helper intrinsics like vec_ctf to generate constants:

• XMVectorSplatOne
• XMVectorSplatInfinity
• XMVectorSplatQNaN
• XMVectorSplatEpsilon
• XMVectorSplatSignMask

For the SSE implementation, they are implemented as just loads from vectorized data-segment constants. It would be nice to find a way to generate the values instead to minimize data read and catch impacts.

For ARM-NEON, most of these use vdupq_n_f32 or vdupq_n_u32 which should be reasonably efficient already.