Added new SIMD unit tests to build scripts.

First working version of ARM NEON 4-SHA256. Though only seeing 16.2 cycles/byte vs. 22.8 cycles/byte for straight SHA256.
Improved ARM NEON 4-SHA256, now does 15.11 cycles/byte. Next thing to do is a 4-loader,
then we can eliminate the ARM<=>NEON intermix which is slow on ARM.