[C++] Implement x86 SIMD-accelerated binary arithmetic kernels

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Reporter: Wes McKinney / @wesm

Related issues:

• [C++] Arithmetic kernels for numeric arrays (is a child of)
• [C++] Implement binary arithmetic kernels for numeric arrays (relates to)

_{Note: This issue was originally created as ARROW-1798. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
This is a large task and probably not very high-priority. Our initial performance focus is more on finding the appropriate abstractions rather than micro-optimizations, except in a few critical places.

[asfimport]

Antoine Pitrou / @pitrou:
I don't think it's worse keeping a generic issue open for this. Interested parties will contribute optimizations when they need them.